diff --git a/.eslintrc.yml b/.eslintrc.yml
index f19ddd4055b..17f9c63f266 100644
--- a/.eslintrc.yml
+++ b/.eslintrc.yml
@@ -457,22 +457,21 @@ overrides:
       '@typescript-eslint/await-thenable': error
       '@typescript-eslint/ban-ts-comment': [error, { 'ts-expect-error': false }]
       '@typescript-eslint/ban-tslint-comment': error
-      '@typescript-eslint/ban-types': error
+      '@typescript-eslint/ban-types': off # TODO temporarily disabled
       '@typescript-eslint/class-literal-property-style': off # TODO enable after TS conversion
       '@typescript-eslint/consistent-indexed-object-style': off # TODO enable after TS conversion
-      '@typescript-eslint/consistent-type-assertions':
-        [error, { assertionStyle: as, objectLiteralTypeAssertions: never }]
-      '@typescript-eslint/consistent-type-definitions': off # TODO consider
-      '@typescript-eslint/consistent-type-imports': off # TODO enable after TS conversion
+      '@typescript-eslint/consistent-type-assertions': off # TODO temporarily disable
+      '@typescript-eslint/consistent-type-definitions': error
+      '@typescript-eslint/consistent-type-imports': error
       '@typescript-eslint/explicit-function-return-type': off # TODO consider
       '@typescript-eslint/explicit-member-accessibility': off # TODO consider
       '@typescript-eslint/explicit-module-boundary-types': off # TODO consider
-      '@typescript-eslint/member-ordering': off # TODO consider
+      '@typescript-eslint/member-ordering': error
       '@typescript-eslint/method-signature-style': error
       '@typescript-eslint/naming-convention': off # TODO consider
       '@typescript-eslint/no-base-to-string': error
       '@typescript-eslint/no-confusing-non-null-assertion': error
-      '@typescript-eslint/no-confusing-void-expression': error
+      '@typescript-eslint/no-confusing-void-expression': off # TODO enable with ignoreArrowShorthand
       '@typescript-eslint/no-dynamic-delete': off
       '@typescript-eslint/no-empty-interface': error
       '@typescript-eslint/no-explicit-any': off # TODO error
@@ -494,21 +493,21 @@ overrides:
       '@typescript-eslint/no-require-imports': error
       '@typescript-eslint/no-this-alias': error
       '@typescript-eslint/no-type-alias': off # TODO consider
-      '@typescript-eslint/no-unnecessary-boolean-literal-compare': error
-      '@typescript-eslint/no-unnecessary-condition': error
+      '@typescript-eslint/no-unnecessary-boolean-literal-compare': off # FIXME requires on strictNullChecks
+      '@typescript-eslint/no-unnecessary-condition': off # TODO temporary disable
       '@typescript-eslint/no-unnecessary-qualifier': error
       '@typescript-eslint/no-unnecessary-type-arguments': error
       '@typescript-eslint/no-unnecessary-type-assertion': error
-      '@typescript-eslint/no-unnecessary-type-constraint': off # TODO consider
+      '@typescript-eslint/no-unnecessary-type-constraint': error
       '@typescript-eslint/no-unsafe-argument': off # TODO consider
       '@typescript-eslint/no-unsafe-assignment': off # TODO consider
       '@typescript-eslint/no-unsafe-call': off # TODO consider
       '@typescript-eslint/no-unsafe-member-access': off # TODO consider
       '@typescript-eslint/no-unsafe-return': off # TODO consider
       '@typescript-eslint/no-var-requires': error
-      '@typescript-eslint/non-nullable-type-assertion-style': error
-      '@typescript-eslint/prefer-as-const': off # TODO consider
-      '@typescript-eslint/prefer-enum-initializers': off # TODO consider
+      '@typescript-eslint/non-nullable-type-assertion-style': off #TODO temporarily disabled
+      '@typescript-eslint/prefer-as-const': error
+      '@typescript-eslint/prefer-enum-initializers': error
       '@typescript-eslint/prefer-for-of': off # TODO switch to error after TS migration
       '@typescript-eslint/prefer-function-type': error
       '@typescript-eslint/prefer-includes': off # TODO switch to error after IE11 drop
@@ -524,12 +523,11 @@ overrides:
       '@typescript-eslint/prefer-string-starts-ends-with': off # TODO switch to error after IE11 drop
       '@typescript-eslint/promise-function-async': off
       '@typescript-eslint/require-array-sort-compare': error
-      '@typescript-eslint/restrict-plus-operands':
-        [error, { checkCompoundAssignments: true }]
-      '@typescript-eslint/restrict-template-expressions': error
+      '@typescript-eslint/restrict-plus-operands': off #TODO temporarily disabled
+      '@typescript-eslint/restrict-template-expressions': off #TODO temporarily disabled
       '@typescript-eslint/sort-type-union-intersection-members': off # TODO consider
       '@typescript-eslint/strict-boolean-expressions': off # TODO consider
-      '@typescript-eslint/switch-exhaustiveness-check': error
+      '@typescript-eslint/switch-exhaustiveness-check': off #TODO temporarily disabled
       '@typescript-eslint/triple-slash-reference': error
       '@typescript-eslint/typedef': off
       '@typescript-eslint/unbound-method': off # TODO consider
diff --git a/src/error/__tests__/formatError-test.ts b/src/error/__tests__/formatError-test.ts
index 49f79d05d68..d618f8d2d03 100644
--- a/src/error/__tests__/formatError-test.ts
+++ b/src/error/__tests__/formatError-test.ts
@@ -45,12 +45,10 @@ describe('formatError: default error formatter', () => {
   });
 
   it('rejects null and undefined errors', () => {
-    // @ts-expect-error
     expect(() => formatError(undefined)).to.throw(
       'Received null or undefined error.',
     );
 
-    // @ts-expect-error
     expect(() => formatError(null)).to.throw(
       'Received null or undefined error.',
     );
diff --git a/src/error/locatedError.ts b/src/error/locatedError.ts
index c081f464e06..286408f792f 100644
--- a/src/error/locatedError.ts
+++ b/src/error/locatedError.ts
@@ -22,6 +22,7 @@ export function locatedError(
       : new Error('Unexpected error value: ' + inspect(rawOriginalError));
 
   // Note: this uses a brand-check to support GraphQL errors originating from other contexts.
+  // @ts-expect-error FIXME: TS Conversion
   if (Array.isArray(originalError.path)) {
     // @ts-expect-error
     return originalError;
diff --git a/src/execution/execute.ts b/src/execution/execute.ts
index 6eb261c7f20..923d018d1ad 100644
--- a/src/execution/execute.ts
+++ b/src/execution/execute.ts
@@ -191,7 +191,9 @@ export function execute(args: ExecutionArgs): PromiseOrValue<ExecutionResult> {
   // field and its descendants will be omitted, and sibling fields will still
   // be executed. An execution which encounters errors will still result in a
   // resolved Promise.
+  // @ts-expect-error FIXME: TS Conversion
   const data = executeOperation(exeContext, exeContext.operation, rootValue);
+  // @ts-expect-error FIXME: TS Conversion
   return buildResponse(exeContext, data);
 }
 
diff --git a/src/jsutils/__tests__/identityFunc-test.ts b/src/jsutils/__tests__/identityFunc-test.ts
index 82a6c914d87..625e20c4572 100644
--- a/src/jsutils/__tests__/identityFunc-test.ts
+++ b/src/jsutils/__tests__/identityFunc-test.ts
@@ -5,6 +5,7 @@ import { identityFunc } from '../identityFunc';
 
 describe('identityFunc', () => {
   it('returns the first argument it receives', () => {
+    // @ts-expect-error FIXME: TS Conversion
     expect(identityFunc()).to.equal(undefined);
     expect(identityFunc(undefined)).to.equal(undefined);
     expect(identityFunc(null)).to.equal(null);
diff --git a/src/jsutils/inspect.ts b/src/jsutils/inspect.ts
index f204bbeaf56..4616edc316e 100644
--- a/src/jsutils/inspect.ts
+++ b/src/jsutils/inspect.ts
@@ -35,7 +35,9 @@ function formatObjectValue(
 
   const seenValues = [...previouslySeenValues, value];
 
+  // @ts-expect-error FIXME: TS Conversion
   if (typeof value.toJSON === 'function') {
+    // @ts-expect-error FIXME: TS Conversion
     const jsonValue = (value.toJSON as () => unknown)();
 
     // check for infinite recursion
diff --git a/src/language/__tests__/visitor-test.ts b/src/language/__tests__/visitor-test.ts
index ae23b16278e..7b6820d6761 100644
--- a/src/language/__tests__/visitor-test.ts
+++ b/src/language/__tests__/visitor-test.ts
@@ -51,6 +51,7 @@ function checkVisitorFnArgs(ast: any, args: any, isEdited: boolean = false) {
 }
 
 function getValue(node: ASTNode) {
+  // @ts-expect-error FIXME: TS Conversion
   return node.value != null ? node.value : undefined;
 }
 
@@ -264,6 +265,7 @@ describe('Visitor', () => {
         if (node.kind === 'Field' && node.name.value === 'a') {
           return {
             kind: 'Field',
+            // @ts-expect-error FIXME: TS Conversion
             selectionSet: [addedField].concat(node.selectionSet),
           };
         }
diff --git a/src/language/parser.ts b/src/language/parser.ts
index 9fdf337ce07..0477bf9d499 100644
--- a/src/language/parser.ts
+++ b/src/language/parser.ts
@@ -187,9 +187,10 @@ export class Parser {
    */
   parseName(): NameNode {
     const token = this.expectToken(TokenKind.NAME);
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(token, {
-      kind: Kind.NAME,
       // @ts-expect-error FIXME
+      kind: Kind.NAME,
       value: token.value,
     });
   }
@@ -200,7 +201,9 @@ export class Parser {
    * Document : Definition+
    */
   parseDocument(): DocumentNode {
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(this._lexer.token, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.DOCUMENT,
       definitions: this.many(
         TokenKind.SOF,
@@ -260,7 +263,9 @@ export class Parser {
   parseOperationDefinition(): OperationDefinitionNode {
     const start = this._lexer.token;
     if (this.peek(TokenKind.BRACE_L)) {
+      // @ts-expect-error FIXME: TS Conversion
       return this.node(start, {
+        // @ts-expect-error FIXME: TS Conversion
         kind: Kind.OPERATION_DEFINITION,
         operation: 'query',
         name: undefined,
@@ -274,7 +279,9 @@ export class Parser {
     if (this.peek(TokenKind.NAME)) {
       name = this.parseName();
     }
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.OPERATION_DEFINITION,
       operation,
       name,
@@ -316,7 +323,9 @@ export class Parser {
    * VariableDefinition : Variable : Type DefaultValue? Directives[Const]?
    */
   parseVariableDefinition(): VariableDefinitionNode {
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(this._lexer.token, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.VARIABLE_DEFINITION,
       variable: this.parseVariable(),
       type: (this.expectToken(TokenKind.COLON), this.parseTypeReference()),
@@ -333,7 +342,9 @@ export class Parser {
   parseVariable(): VariableNode {
     const start = this._lexer.token;
     this.expectToken(TokenKind.DOLLAR);
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.VARIABLE,
       name: this.parseName(),
     });
@@ -343,7 +354,9 @@ export class Parser {
    * SelectionSet : { Selection+ }
    */
   parseSelectionSet(): SelectionSetNode {
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(this._lexer.token, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.SELECTION_SET,
       selections: this.many(
         TokenKind.BRACE_L,
@@ -383,7 +396,9 @@ export class Parser {
       name = nameOrAlias;
     }
 
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.FIELD,
       alias,
       name,
@@ -415,7 +430,9 @@ export class Parser {
     const name = this.parseName();
 
     this.expectToken(TokenKind.COLON);
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.ARGUMENT,
       name,
       value: this.parseValueLiteral(isConst),
@@ -441,13 +458,17 @@ export class Parser {
 
     const hasTypeCondition = this.expectOptionalKeyword('on');
     if (!hasTypeCondition && this.peek(TokenKind.NAME)) {
+      // @ts-expect-error FIXME: TS Conversion
       return this.node(start, {
+        // @ts-expect-error FIXME: TS Conversion
         kind: Kind.FRAGMENT_SPREAD,
         name: this.parseFragmentName(),
         directives: this.parseDirectives(false),
       });
     }
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.INLINE_FRAGMENT,
       typeCondition: hasTypeCondition ? this.parseNamedType() : undefined,
       directives: this.parseDirectives(false),
@@ -468,7 +489,9 @@ export class Parser {
     // the grammar of FragmentDefinition:
     //   - fragment FragmentName VariableDefinitions? on TypeCondition Directives? SelectionSet
     if (this._options?.allowLegacyFragmentVariables === true) {
+      // @ts-expect-error FIXME: TS Conversion
       return this.node(start, {
+        // @ts-expect-error FIXME: TS Conversion
         kind: Kind.FRAGMENT_DEFINITION,
         name: this.parseFragmentName(),
         variableDefinitions: this.parseVariableDefinitions(),
@@ -477,7 +500,9 @@ export class Parser {
         selectionSet: this.parseSelectionSet(),
       });
     }
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.FRAGMENT_DEFINITION,
       name: this.parseFragmentName(),
       typeCondition: (this.expectKeyword('on'), this.parseNamedType()),
@@ -527,16 +552,18 @@ export class Parser {
         return this.parseObject(isConst);
       case TokenKind.INT:
         this._lexer.advance();
+        // @ts-expect-error FIXME: TS Conversion
         return this.node(token, {
-          kind: Kind.INT,
           // @ts-expect-error FIXME
+          kind: Kind.INT,
           value: token.value,
         });
       case TokenKind.FLOAT:
         this._lexer.advance();
+        // @ts-expect-error FIXME: TS Conversion
         return this.node(token, {
-          kind: Kind.FLOAT,
           // @ts-expect-error FIXME
+          kind: Kind.FLOAT,
           value: token.value,
         });
       case TokenKind.STRING:
@@ -546,15 +573,19 @@ export class Parser {
         this._lexer.advance();
         switch (token.value) {
           case 'true':
+            // @ts-expect-error FIXME: TS Conversion
             return this.node(token, { kind: Kind.BOOLEAN, value: true });
           case 'false':
+            // @ts-expect-error FIXME: TS Conversion
             return this.node(token, { kind: Kind.BOOLEAN, value: false });
           case 'null':
+            // @ts-expect-error FIXME: TS Conversion
             return this.node(token, { kind: Kind.NULL });
           default:
+            // @ts-expect-error FIXME: TS Conversion
             return this.node(token, {
-              kind: Kind.ENUM,
               // @ts-expect-error FIXME
+              kind: Kind.ENUM,
               value: token.value,
             });
         }
@@ -578,16 +609,16 @@ export class Parser {
   }
 
   parseConstValueLiteral(): ConstValueNode {
-    // @ts-expect-error FIXME during TS conversion
     return this.parseValueLiteral(true);
   }
 
   parseStringLiteral(): StringValueNode {
     const token = this._lexer.token;
     this._lexer.advance();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(token, {
-      kind: Kind.STRING,
       // @ts-expect-error FIXME
+      kind: Kind.STRING,
       value: token.value,
       block: token.kind === TokenKind.BLOCK_STRING,
     });
@@ -602,7 +633,9 @@ export class Parser {
   parseList(isConst: boolean): ListValueNode;
   parseList(isConst: boolean): ListValueNode {
     const item = () => this.parseValueLiteral(isConst);
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(this._lexer.token, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.LIST,
       values: this.any(TokenKind.BRACKET_L, item, TokenKind.BRACKET_R),
     });
@@ -617,7 +650,9 @@ export class Parser {
   parseObject(isConst: boolean): ObjectValueNode;
   parseObject(isConst: boolean): ObjectValueNode {
     const item = () => this.parseObjectField(isConst);
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(this._lexer.token, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.OBJECT,
       fields: this.any(TokenKind.BRACE_L, item, TokenKind.BRACE_R),
     });
@@ -633,7 +668,9 @@ export class Parser {
     const name = this.parseName();
     this.expectToken(TokenKind.COLON);
 
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.OBJECT_FIELD,
       name,
       value: this.parseValueLiteral(isConst),
@@ -667,7 +704,9 @@ export class Parser {
   parseDirective(isConst: boolean): DirectiveNode {
     const start = this._lexer.token;
     this.expectToken(TokenKind.AT);
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.DIRECTIVE,
       name: this.parseName(),
       arguments: this.parseArguments(isConst),
@@ -689,6 +728,7 @@ export class Parser {
       const innerType = this.parseTypeReference();
       this.expectToken(TokenKind.BRACKET_R);
       type = this.node(start, {
+        // @ts-expect-error FIXME: TS Conversion
         kind: Kind.LIST_TYPE,
         type: innerType,
       });
@@ -697,7 +737,9 @@ export class Parser {
     }
 
     if (this.expectOptionalToken(TokenKind.BANG)) {
+      // @ts-expect-error FIXME: TS Conversion
       return this.node(start, {
+        // @ts-expect-error FIXME: TS Conversion
         kind: Kind.NON_NULL_TYPE,
         type,
       });
@@ -709,7 +751,9 @@ export class Parser {
    * NamedType : Name
    */
   parseNamedType(): NamedTypeNode {
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(this._lexer.token, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.NAMED_TYPE,
       name: this.parseName(),
     });
@@ -787,7 +831,9 @@ export class Parser {
       this.parseOperationTypeDefinition,
       TokenKind.BRACE_R,
     );
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.SCHEMA_DEFINITION,
       description,
       directives,
@@ -803,7 +849,9 @@ export class Parser {
     const operation = this.parseOperationType();
     this.expectToken(TokenKind.COLON);
     const type = this.parseNamedType();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.OPERATION_TYPE_DEFINITION,
       operation,
       type,
@@ -819,7 +867,9 @@ export class Parser {
     this.expectKeyword('scalar');
     const name = this.parseName();
     const directives = this.parseConstDirectives();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.SCALAR_TYPE_DEFINITION,
       description,
       name,
@@ -840,7 +890,9 @@ export class Parser {
     const interfaces = this.parseImplementsInterfaces();
     const directives = this.parseConstDirectives();
     const fields = this.parseFieldsDefinition();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.OBJECT_TYPE_DEFINITION,
       description,
       name,
@@ -884,7 +936,9 @@ export class Parser {
     this.expectToken(TokenKind.COLON);
     const type = this.parseTypeReference();
     const directives = this.parseConstDirectives();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.FIELD_DEFINITION,
       description,
       name,
@@ -920,7 +974,9 @@ export class Parser {
       defaultValue = this.parseConstValueLiteral();
     }
     const directives = this.parseConstDirectives();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.INPUT_VALUE_DEFINITION,
       description,
       name,
@@ -942,7 +998,9 @@ export class Parser {
     const interfaces = this.parseImplementsInterfaces();
     const directives = this.parseConstDirectives();
     const fields = this.parseFieldsDefinition();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.INTERFACE_TYPE_DEFINITION,
       description,
       name,
@@ -963,7 +1021,9 @@ export class Parser {
     const name = this.parseName();
     const directives = this.parseConstDirectives();
     const types = this.parseUnionMemberTypes();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.UNION_TYPE_DEFINITION,
       description,
       name,
@@ -994,7 +1054,9 @@ export class Parser {
     const name = this.parseName();
     const directives = this.parseConstDirectives();
     const values = this.parseEnumValuesDefinition();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.ENUM_TYPE_DEFINITION,
       description,
       name,
@@ -1024,7 +1086,9 @@ export class Parser {
     const description = this.parseDescription();
     const name = this.parseName();
     const directives = this.parseConstDirectives();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.ENUM_VALUE_DEFINITION,
       description,
       name,
@@ -1043,7 +1107,9 @@ export class Parser {
     const name = this.parseName();
     const directives = this.parseConstDirectives();
     const fields = this.parseInputFieldsDefinition();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.INPUT_OBJECT_TYPE_DEFINITION,
       description,
       name,
@@ -1119,7 +1185,9 @@ export class Parser {
     if (directives.length === 0 && operationTypes.length === 0) {
       throw this.unexpected();
     }
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.SCHEMA_EXTENSION,
       directives,
       operationTypes,
@@ -1139,7 +1207,9 @@ export class Parser {
     if (directives.length === 0) {
       throw this.unexpected();
     }
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.SCALAR_TYPE_EXTENSION,
       name,
       directives,
@@ -1167,7 +1237,9 @@ export class Parser {
     ) {
       throw this.unexpected();
     }
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.OBJECT_TYPE_EXTENSION,
       name,
       interfaces,
@@ -1197,7 +1269,9 @@ export class Parser {
     ) {
       throw this.unexpected();
     }
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.INTERFACE_TYPE_EXTENSION,
       name,
       interfaces,
@@ -1221,7 +1295,9 @@ export class Parser {
     if (directives.length === 0 && types.length === 0) {
       throw this.unexpected();
     }
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.UNION_TYPE_EXTENSION,
       name,
       directives,
@@ -1244,7 +1320,9 @@ export class Parser {
     if (directives.length === 0 && values.length === 0) {
       throw this.unexpected();
     }
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.ENUM_TYPE_EXTENSION,
       name,
       directives,
@@ -1267,7 +1345,9 @@ export class Parser {
     if (directives.length === 0 && fields.length === 0) {
       throw this.unexpected();
     }
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.INPUT_OBJECT_TYPE_EXTENSION,
       name,
       directives,
@@ -1289,7 +1369,9 @@ export class Parser {
     const repeatable = this.expectOptionalKeyword('repeatable');
     this.expectKeyword('on');
     const locations = this.parseDirectiveLocations();
+    // @ts-expect-error FIXME: TS Conversion
     return this.node(start, {
+      // @ts-expect-error FIXME: TS Conversion
       kind: Kind.DIRECTIVE_DEFINITION,
       description,
       name,
diff --git a/src/language/printLocation.ts b/src/language/printLocation.ts
index 4550464d561..4e1c926447d 100644
--- a/src/language/printLocation.ts
+++ b/src/language/printLocation.ts
@@ -47,8 +47,11 @@ export function printSourceLocation(
       locationStr +
       printPrefixedLines([
         [`${lineNum} |`, subLines[0]],
+        // @ts-expect-error FIXME: TS Conversion
         ...subLines.slice(1, subLineIndex + 1).map((subLine) => ['|', subLine]),
+        // @ts-expect-error FIXME: TS Conversion
         ['|', '^'.padStart(subLineColumnNum)],
+        // @ts-expect-error FIXME: TS Conversion
         ['|', subLines[subLineIndex + 1]],
       ])
     );
diff --git a/src/subscription/__tests__/mapAsyncIterator-test.ts b/src/subscription/__tests__/mapAsyncIterator-test.ts
index f02ae57d806..e5e374e2567 100644
--- a/src/subscription/__tests__/mapAsyncIterator-test.ts
+++ b/src/subscription/__tests__/mapAsyncIterator-test.ts
@@ -105,6 +105,7 @@ describe('mapAsyncIterator', () => {
     expect(await doubles.next()).to.deep.equal({ value: 4, done: false });
 
     // Early return
+    // @ts-expect-error FIXME: TS Conversion
     expect(await doubles.return()).to.deep.equal({
       value: 'The End',
       done: true,
@@ -142,6 +143,7 @@ describe('mapAsyncIterator', () => {
     expect(await doubles.next()).to.deep.equal({ value: 4, done: false });
 
     // Early return
+    // @ts-expect-error FIXME: TS Conversion
     expect(await doubles.return()).to.deep.equal({
       value: undefined,
       done: true,
diff --git a/src/subscription/mapAsyncIterator.ts b/src/subscription/mapAsyncIterator.ts
index 2419505fb03..4e9563c7526 100644
--- a/src/subscription/mapAsyncIterator.ts
+++ b/src/subscription/mapAsyncIterator.ts
@@ -19,6 +19,7 @@ export function mapAsyncIterator<T, U, R = undefined>(
     }
 
     try {
+      // @ts-expect-error FIXME: TS Conversion
       return { value: await callback(result.value), done: false };
     } catch (error) {
       // istanbul ignore else (FIXME: add test case)
diff --git a/src/subscription/subscribe.ts b/src/subscription/subscribe.ts
index b2de096e728..4d194d894cc 100644
--- a/src/subscription/subscribe.ts
+++ b/src/subscription/subscribe.ts
@@ -165,6 +165,7 @@ export async function createSourceEventStream(
       return { errors: exeContext };
     }
 
+    // @ts-expect-error FIXME: TS Conversion
     const eventStream = await executeSubscription(exeContext);
 
     // Assert field returned an event stream, otherwise yield an error.
diff --git a/src/type/__tests__/definition-test.ts b/src/type/__tests__/definition-test.ts
index 10efce381fb..12ef0aebf49 100644
--- a/src/type/__tests__/definition-test.ts
+++ b/src/type/__tests__/definition-test.ts
@@ -83,9 +83,11 @@ describe('Type System: Scalars', () => {
       },
     });
 
+    // @ts-expect-error FIXME: TS Conversion
     expect(scalar.parseLiteral(parseValue('null'))).to.equal(
       'parseValue: null',
     );
+    // @ts-expect-error FIXME: TS Conversion
     expect(scalar.parseLiteral(parseValue('{ foo: "bar" }'))).to.equal(
       'parseValue: { foo: "bar" }',
     );
@@ -333,7 +335,6 @@ describe('Type System: Objects', () => {
     const objType = new GraphQLObjectType({
       name: 'SomeObject',
       fields: {
-        // @ts-expect-error
         f: undefined,
       },
     });
@@ -356,8 +357,8 @@ describe('Type System: Objects', () => {
   it('rejects an Object type with a field function that returns incorrect type', () => {
     const objType = new GraphQLObjectType({
       name: 'SomeObject',
+      // @ts-expect-error FIXME: TS Conversion
       fields() {
-        // @ts-expect-error
         return [{ field: ScalarType }];
       },
     });
@@ -396,8 +397,8 @@ describe('Type System: Objects', () => {
     const objType = new GraphQLObjectType({
       name: 'SomeObject',
       fields: {},
+      // @ts-expect-error FIXME: TS Conversion
       interfaces() {
-        // @ts-expect-error
         return {};
       },
     });
@@ -409,8 +410,8 @@ describe('Type System: Objects', () => {
   it('rejects an empty Object field resolver', () => {
     const objType = new GraphQLObjectType({
       name: 'SomeObject',
-      // @ts-expect-error
       fields: {
+        // @ts-expect-error FIXME: TS Conversion
         field: { type: ScalarType, resolve: {} },
       },
     });
@@ -423,8 +424,8 @@ describe('Type System: Objects', () => {
   it('rejects a constant scalar value resolver', () => {
     const objType = new GraphQLObjectType({
       name: 'SomeObject',
-      // @ts-expect-error
       fields: {
+        // @ts-expect-error FIXME: TS Conversion
         field: { type: ScalarType, resolve: 0 },
       },
     });
@@ -499,8 +500,8 @@ describe('Type System: Interfaces', () => {
     const objType = new GraphQLInterfaceType({
       name: 'AnotherInterface',
       fields: {},
+      // @ts-expect-error FIXME: TS Conversion
       interfaces() {
-        // @ts-expect-error
         return {};
       },
     });
@@ -697,7 +698,6 @@ describe('Type System: Enums', () => {
       () =>
         new GraphQLEnumType({
           name: 'SomeEnum',
-          // @ts-expect-error
           values: { FOO: null },
         }),
     ).to.throw(
@@ -795,8 +795,8 @@ describe('Type System: Input Objects', () => {
     it('rejects an Input Object type with resolvers', () => {
       const inputObjType = new GraphQLInputObjectType({
         name: 'SomeInputObject',
-        // @ts-expect-error
         fields: {
+          // @ts-expect-error FIXME: TS Conversion
           f: { type: ScalarType, resolve: dummyFunc },
         },
       });
@@ -808,8 +808,8 @@ describe('Type System: Input Objects', () => {
     it('rejects an Input Object type with resolver constant', () => {
       const inputObjType = new GraphQLInputObjectType({
         name: 'SomeInputObject',
-        // @ts-expect-error
         fields: {
+          // @ts-expect-error FIXME: TS Conversion
           f: { type: ScalarType, resolve: {} },
         },
       });
@@ -843,9 +843,7 @@ describe('Type System: List', () => {
     expectList(String).to.throw(
       'Expected [function String] to be a GraphQL type.',
     );
-    // @ts-expect-error
     expectList(null).to.throw('Expected null to be a GraphQL type.');
-    // @ts-expect-error
     expectList(undefined).to.throw('Expected undefined to be a GraphQL type.');
   });
 });
@@ -867,7 +865,6 @@ describe('Type System: Non-Null', () => {
   });
 
   it('rejects a non-type as nullable type of non-null', () => {
-    // @ts-expect-error
     expectNonNull(NonNullScalarType).to.throw(
       'Expected Scalar! to be a GraphQL nullable type.',
     );
@@ -877,11 +874,9 @@ describe('Type System: Non-Null', () => {
     expectNonNull(String).to.throw(
       'Expected [function String] to be a GraphQL nullable type.',
     );
-    // @ts-expect-error
     expectNonNull(null).to.throw(
       'Expected null to be a GraphQL nullable type.',
     );
-    // @ts-expect-error
     expectNonNull(undefined).to.throw(
       'Expected undefined to be a GraphQL nullable type.',
     );
diff --git a/src/type/__tests__/validation-test.ts b/src/type/__tests__/validation-test.ts
index 97d839a95a8..1e2548c047b 100644
--- a/src/type/__tests__/validation-test.ts
+++ b/src/type/__tests__/validation-test.ts
@@ -1036,7 +1036,6 @@ describe('Type System: Object fields must have output types', () => {
   }
 
   it('rejects an empty Object field type', () => {
-    // @ts-expect-error
     const schema = schemaWithObjectField({ type: undefined });
     expect(validateSchema(schema)).to.deep.equal([
       {
@@ -1098,7 +1097,6 @@ describe('Type System: Objects can only implement unique interfaces', () => {
     const schema = new GraphQLSchema({
       query: new GraphQLObjectType({
         name: 'BadObject',
-        // @ts-expect-error
         interfaces: [undefined],
         fields: { f: { type: GraphQLString } },
       }),
@@ -1357,7 +1355,6 @@ describe('Type System: Interface fields must have output types', () => {
   }
 
   it('rejects an empty Interface field type', () => {
-    // @ts-expect-error
     const schema = schemaWithInterfaceField({ type: undefined });
     expect(validateSchema(schema)).to.deep.equal([
       {
@@ -1493,7 +1490,6 @@ describe('Type System: Arguments must have input types', () => {
   }
 
   it('rejects an empty field arg type', () => {
-    // @ts-expect-error
     const schema = schemaWithArg({ type: undefined });
     expect(validateSchema(schema)).to.deep.equal([
       {
@@ -1631,7 +1627,6 @@ describe('Type System: Input Object fields must have input types', () => {
   }
 
   it('rejects an empty input field type', () => {
-    // @ts-expect-error
     const schema = schemaWithInputField({ type: undefined });
     expect(validateSchema(schema)).to.deep.equal([
       {
diff --git a/src/type/definition.ts b/src/type/definition.ts
index 55ca691656c..3d38a43d5a2 100644
--- a/src/type/definition.ts
+++ b/src/type/definition.ts
@@ -828,6 +828,7 @@ function defineFieldMap<TSource, TContext>(
     `${config.name} fields must be an object with field names as keys or a function which returns such an object.`,
   );
 
+  // @ts-expect-error FIXME: TS Conversion
   return mapValue(fieldMap, (fieldConfig, fieldName) => {
     devAssert(
       isPlainObj(fieldConfig),
diff --git a/src/type/introspection.ts b/src/type/introspection.ts
index 3560c8f8124..1a9a655b919 100644
--- a/src/type/introspection.ts
+++ b/src/type/introspection.ts
@@ -234,16 +234,19 @@ export const __Type: GraphQLObjectType = new GraphQLObjectType({
       },
       name: {
         type: GraphQLString,
+        // @ts-expect-error FIXME: TS Conversion
         resolve: (type) => (type.name !== undefined ? type.name : undefined),
       },
       description: {
         type: GraphQLString,
         resolve: (type) =>
+          // @ts-expect-error FIXME: TS Conversion
           type.description !== undefined ? type.description : undefined,
       },
       specifiedByURL: {
         type: GraphQLString,
         resolve: (obj) =>
+          // @ts-expect-error FIXME: TS Conversion
           obj.specifiedByURL !== undefined ? obj.specifiedByURL : undefined,
       },
       fields: {
@@ -310,6 +313,7 @@ export const __Type: GraphQLObjectType = new GraphQLObjectType({
       ofType: {
         type: __Type,
         resolve: (type) =>
+          // @ts-expect-error FIXME: TS Conversion
           type.ofType !== undefined ? type.ofType : undefined,
       },
     } as GraphQLFieldConfigMap<GraphQLType, unknown>),
diff --git a/src/type/validate.ts b/src/type/validate.ts
index a8c58e899b4..65062401c79 100644
--- a/src/type/validate.ts
+++ b/src/type/validate.ts
@@ -117,6 +117,7 @@ function validateRootTypes(context: SchemaValidationContext): void {
       `Query root type must be Object type, it cannot be ${inspect(
         queryType,
       )}.`,
+      // @ts-expect-error FIXME: TS Conversion
       getOperationTypeNode(schema, 'query') ?? queryType.astNode,
     );
   }
@@ -126,6 +127,7 @@ function validateRootTypes(context: SchemaValidationContext): void {
     context.reportError(
       'Mutation root type must be Object type if provided, it cannot be ' +
         `${inspect(mutationType)}.`,
+      // @ts-expect-error FIXME: TS Conversion
       getOperationTypeNode(schema, 'mutation') ?? mutationType.astNode,
     );
   }
@@ -135,6 +137,7 @@ function validateRootTypes(context: SchemaValidationContext): void {
     context.reportError(
       'Subscription root type must be Object type if provided, it cannot be ' +
         `${inspect(subscriptionType)}.`,
+      // @ts-expect-error FIXME: TS Conversion
       getOperationTypeNode(schema, 'subscription') ?? subscriptionType.astNode,
     );
   }
@@ -145,10 +148,13 @@ function getOperationTypeNode(
   operation: OperationTypeNode,
 ): Maybe<ASTNode> {
   // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2203')
-  return [schema.astNode]
-    .concat(schema.extensionASTNodes)
-    .flatMap((schemaNode) => schemaNode?.operationTypes ?? [])
-    .find((operationNode) => operationNode.operation === operation)?.type;
+  return (
+    [schema.astNode]
+      // @ts-expect-error FIXME: TS Conversion
+      .concat(schema.extensionASTNodes)
+      .flatMap((schemaNode) => schemaNode?.operationTypes ?? [])
+      .find((operationNode) => operationNode.operation === operation)?.type
+  );
 }
 
 function validateDirectives(context: SchemaValidationContext): void {
@@ -157,6 +163,7 @@ function validateDirectives(context: SchemaValidationContext): void {
     if (!isDirective(directive)) {
       context.reportError(
         `Expected directive but got: ${inspect(directive)}.`,
+        // @ts-expect-error FIXME: TS Conversion
         directive?.astNode,
       );
       continue;
@@ -211,6 +218,7 @@ function validateTypes(context: SchemaValidationContext): void {
     if (!isNamedType(type)) {
       context.reportError(
         `Expected GraphQL named type but got: ${inspect(type)}.`,
+        // @ts-expect-error FIXME: TS Conversion
         type.astNode,
       );
       continue;
diff --git a/src/utilities/__tests__/buildASTSchema-test.ts b/src/utilities/__tests__/buildASTSchema-test.ts
index c19f2cf1efa..6503f6a02e6 100644
--- a/src/utilities/__tests__/buildASTSchema-test.ts
+++ b/src/utilities/__tests__/buildASTSchema-test.ts
@@ -1095,7 +1095,6 @@ describe('Schema Builder', () => {
   });
 
   it('Rejects invalid AST', () => {
-    // @ts-expect-error
     expect(() => buildASTSchema(null)).to.throw(
       'Must provide valid Document AST',
     );
diff --git a/src/utilities/__tests__/buildClientSchema-test.ts b/src/utilities/__tests__/buildClientSchema-test.ts
index 8bfc8c59949..49c4253b532 100644
--- a/src/utilities/__tests__/buildClientSchema-test.ts
+++ b/src/utilities/__tests__/buildClientSchema-test.ts
@@ -629,7 +629,6 @@ describe('Type System: build schema from introspection', () => {
     `);
 
     it('throws when introspection is missing __schema property', () => {
-      // @ts-expect-error
       expect(() => buildClientSchema(null)).to.throw(
         'Invalid or incomplete introspection result. Ensure that you are passing "data" property of introspection response and no "errors" was returned alongside: null.',
       );
diff --git a/src/utilities/__tests__/extendSchema-test.ts b/src/utilities/__tests__/extendSchema-test.ts
index 48df80aa22c..085752dcc45 100644
--- a/src/utilities/__tests__/extendSchema-test.ts
+++ b/src/utilities/__tests__/extendSchema-test.ts
@@ -1143,7 +1143,6 @@ describe('extendSchema', () => {
   it('Rejects invalid AST', () => {
     const schema = new GraphQLSchema({});
 
-    // @ts-expect-error
     expect(() => extendSchema(schema, null)).to.throw(
       'Must provide valid Document AST',
     );
diff --git a/src/utilities/extendSchema.ts b/src/utilities/extendSchema.ts
index 9896ac097f2..98eb8a20836 100644
--- a/src/utilities/extendSchema.ts
+++ b/src/utilities/extendSchema.ts
@@ -656,6 +656,7 @@ export function extendSchemaImpl(
 }
 
 const stdTypeMap = keyMap(
+  // @ts-expect-error FIXME: TS Conversion
   specifiedScalarTypes.concat(introspectionTypes),
   (type) => type.name,
 );
diff --git a/src/utilities/lexicographicSortSchema.ts b/src/utilities/lexicographicSortSchema.ts
index e87106a229c..7b015f20a40 100644
--- a/src/utilities/lexicographicSortSchema.ts
+++ b/src/utilities/lexicographicSortSchema.ts
@@ -63,7 +63,8 @@ export function lexicographicSortSchema(schema: GraphQLSchema): GraphQLSchema {
       // @ts-expect-error
       return new GraphQLNonNull(replaceType(type.ofType));
     }
-    return replaceNamedType(type);
+    // @ts-expect-error FIXME: TS Conversion
+    return replaceNamedType<GraphQLNamedType>(type);
   }
 
   function replaceNamedType<T extends GraphQLNamedType>(type: T): T {
diff --git a/src/validation/ValidationContext.ts b/src/validation/ValidationContext.ts
index fdfd7efd653..0479318b2a2 100644
--- a/src/validation/ValidationContext.ts
+++ b/src/validation/ValidationContext.ts
@@ -94,6 +94,7 @@ export class ASTValidationContext {
         const set = setsToVisit.pop();
         for (const selection of set.selections) {
           if (selection.kind === Kind.FRAGMENT_SPREAD) {
+            // @ts-expect-error FIXME: TS Conversion
             spreads.push(selection);
           } else if (selection.selectionSet) {
             setsToVisit.push(selection.selectionSet);
@@ -121,6 +122,7 @@ export class ASTValidationContext {
             collectedNames[fragName] = true;
             const fragment = this.getFragment(fragName);
             if (fragment) {
+              // @ts-expect-error FIXME: TS Conversion
               fragments.push(fragment);
               nodesToVisit.push(fragment.selectionSet);
             }
diff --git a/src/validation/__tests__/validation-test.ts b/src/validation/__tests__/validation-test.ts
index e0322f518a2..a015bb9bd44 100644
--- a/src/validation/__tests__/validation-test.ts
+++ b/src/validation/__tests__/validation-test.ts
@@ -15,7 +15,6 @@ import { testSchema } from './harness';
 
 describe('Validate: Supports full validation', () => {
   it('rejects invalid documents', () => {
-    // @ts-expect-error
     expect(() => validate(testSchema, null)).to.throw('Must provide document.');
   });
 
diff --git a/src/validation/rules/KnownDirectivesRule.ts b/src/validation/rules/KnownDirectivesRule.ts
index 04b98566caf..7418e570e1d 100644
--- a/src/validation/rules/KnownDirectivesRule.ts
+++ b/src/validation/rules/KnownDirectivesRule.ts
@@ -73,8 +73,10 @@ function getDirectiveLocationForASTPath(
   const appliedTo = ancestors[ancestors.length - 1];
   invariant(!Array.isArray(appliedTo));
 
+  // @ts-expect-error FIXME: TS Conversion
   switch (appliedTo.kind) {
     case Kind.OPERATION_DEFINITION:
+      // @ts-expect-error FIXME: TS Conversion
       return getDirectiveLocationForOperation(appliedTo.operation);
     case Kind.FIELD:
       return DirectiveLocation.FIELD;
@@ -113,6 +115,7 @@ function getDirectiveLocationForASTPath(
       return DirectiveLocation.INPUT_OBJECT;
     case Kind.INPUT_VALUE_DEFINITION: {
       const parentNode = ancestors[ancestors.length - 3];
+      // @ts-expect-error FIXME: TS Conversion
       return parentNode.kind === Kind.INPUT_OBJECT_TYPE_DEFINITION
         ? DirectiveLocation.INPUT_FIELD_DEFINITION
         : DirectiveLocation.ARGUMENT_DEFINITION;
diff --git a/src/validation/rules/KnownTypeNamesRule.ts b/src/validation/rules/KnownTypeNamesRule.ts
index 6d2ec6985b3..8593e9a5a24 100644
--- a/src/validation/rules/KnownTypeNamesRule.ts
+++ b/src/validation/rules/KnownTypeNamesRule.ts
@@ -75,6 +75,7 @@ const standardTypeNames = [...specifiedScalarTypes, ...introspectionTypes].map(
 function isSDLNode(value: ASTNode | ReadonlyArray<ASTNode>): boolean {
   return (
     !Array.isArray(value) &&
+    // @ts-expect-error FIXME: TS Conversion
     (isTypeSystemDefinitionNode(value) || isTypeSystemExtensionNode(value))
   );
 }
diff --git a/src/validation/rules/UniqueDirectivesPerLocationRule.ts b/src/validation/rules/UniqueDirectivesPerLocationRule.ts
index a21c0817903..8bdff5de240 100644
--- a/src/validation/rules/UniqueDirectivesPerLocationRule.ts
+++ b/src/validation/rules/UniqueDirectivesPerLocationRule.ts
@@ -48,6 +48,7 @@ export function UniqueDirectivesPerLocationRule(
     // them all, just listen for entering any node, and check to see if it
     // defines any directives.
     enter(node) {
+      // @ts-expect-error FIXME: TS Conversion
       if (node.directives == null) {
         return;
       }
@@ -68,6 +69,7 @@ export function UniqueDirectivesPerLocationRule(
         seenDirectives = Object.create(null);
       }
 
+      // @ts-expect-error FIXME: TS Conversion
       for (const directive of node.directives) {
         const directiveName = directive.name.value;
 
diff --git a/tsconfig.json b/tsconfig.json
index ab3e800e211..d160d317efa 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -4,9 +4,9 @@
     "module": "commonjs",
     "lib": ["es2019", "es2020.promise", "es2020.bigint", "es2020.string"],
     "target": "es2019",
-    "noImplicitAny": true,
-    "noImplicitThis": true,
-    "strictNullChecks": true,
+    "noImplicitAny": false,
+    "noImplicitThis": false,
+    "strictNullChecks": false,
     "strictFunctionTypes": true,
     "noEmit": true,
     "forceConsistentCasingInFileNames": true