diff --git a/cli/CHANGELOG.md b/cli/CHANGELOG.md
index de12ae239f90..dd040dab8d4a 100644
--- a/cli/CHANGELOG.md
+++ b/cli/CHANGELOG.md
@@ -12,6 +12,10 @@ _Released 9/25/2024_
 - Fixed an issue where Firefox was incorrectly mutating the state of click events on checkboxes after Firefox version `129` and up. Addressed in [#30245](https://github.com/cypress-io/cypress/pull/30245).
 - Fixed a regression introduced in 13.13.0 where 'Open in IDE' would not work for filepaths containing spaces and various other characters on Windows. Addresses [#29820](https://github.com/cypress-io/cypress/issues/29820).
 
+**Bugfixes:**
+
+- Fixed an issue where run Cypress internal unit test cases error on Windows. Addressed in [#30157](https://github.com/cypress-io/cypress/pull/30157)
+
 **Misc:**
 
 - Pass along the related log to the `createSnapshot` function for protocol usage. Addressed in [#30244](https://github.com/cypress-io/cypress/pull/30244).
diff --git a/packages/data-context/src/codegen/code-generator.ts b/packages/data-context/src/codegen/code-generator.ts
index f9c7250797a8..3b7be1fcb3a4 100644
--- a/packages/data-context/src/codegen/code-generator.ts
+++ b/packages/data-context/src/codegen/code-generator.ts
@@ -5,6 +5,7 @@ import * as ejs from 'ejs'
 import fm from 'front-matter'
 import _ from 'lodash'
 import Debug from 'debug'
+import { toOS } from '../util'
 
 const debug = Debug('cypress:data-context:codegen:code-generator')
 
@@ -179,7 +180,7 @@ export async function hasNonExampleSpec (testTemplateDir: string, specs: string[
     return templateFiles.some((templateFile) => templateFile.substring(testTemplateDir.length + 1) === spec)
   }
 
-  return specs.some((spec) => !specInTemplates(spec))
+  return specs.map(((spec) => toOS(spec))).some((spec) => !specInTemplates(spec))
 }
 
 export async function getExampleSpecPaths (testTemplateDir: string): Promise<string[]> {
diff --git a/packages/data-context/src/sources/FileDataSource.ts b/packages/data-context/src/sources/FileDataSource.ts
index 7c2b1d52f6be..f36149d70680 100644
--- a/packages/data-context/src/sources/FileDataSource.ts
+++ b/packages/data-context/src/sources/FileDataSource.ts
@@ -5,7 +5,7 @@ import os from 'os'
 
 import globby, { GlobbyOptions } from 'globby'
 import Debug from 'debug'
-import { toPosix } from '../util/file'
+import { toOS, toPosix } from '../util/file'
 
 const debug = Debug('cypress:data-context:sources:FileDataSource')
 
@@ -36,14 +36,15 @@ export class FileDataSource {
 
   async getFilesByGlob (cwd: string, glob: string | string[], globOptions: GlobbyOptions = {}): Promise<string[]> {
     const globs = ([] as string[]).concat(glob).map((globPattern) => {
-      const workingDirectoryPrefix = path.join(cwd, path.sep)
+      const workingDirectoryPrefix = toOS(path.join(cwd, path.sep))
+      const globPatternWithOS = toOS(globPattern)
 
       // If the pattern includes the working directory, we strip it from the pattern.
       // The working directory path may include characters that conflict with glob
       // syntax (brackets, parentheses, etc.) and cause our searches to inadvertently fail.
       // We scope our search to the working directory using the `cwd` globby option.
-      if (globPattern.startsWith(workingDirectoryPrefix)) {
-        return globPattern.replace(workingDirectoryPrefix, '')
+      if (globPatternWithOS.startsWith(workingDirectoryPrefix)) {
+        return globPatternWithOS.replace(workingDirectoryPrefix, '')
       }
 
       return globPattern
diff --git a/packages/data-context/src/util/file.ts b/packages/data-context/src/util/file.ts
index 307d4f782092..0415db4f256c 100644
--- a/packages/data-context/src/util/file.ts
+++ b/packages/data-context/src/util/file.ts
@@ -3,3 +3,16 @@ import path from 'path'
 export function toPosix (file: string, sep: string = path.sep) {
   return file.split(sep).join(path.posix.sep)
 }
+
+/**
+ * Converts a POSIX file path to the current operating system's file path format.
+ *
+ * This function takes a file path string that uses POSIX separators ('/') and
+ * replaces them with the current operating system's path separators.
+ *
+ * @param file The file path to convert.
+ * @returns The converted file path with the current OS's path separators.
+ */
+export function toOS (file: string) {
+  return file.split(path.posix.sep).join(path.sep)
+}
diff --git a/packages/data-context/test/unit/codegen/code-generator.spec.ts b/packages/data-context/test/unit/codegen/code-generator.spec.ts
index 01964fec5002..b3df266a0490 100644
--- a/packages/data-context/test/unit/codegen/code-generator.spec.ts
+++ b/packages/data-context/test/unit/codegen/code-generator.spec.ts
@@ -1,6 +1,5 @@
 import { parse } from '@babel/parser'
 import { expect } from 'chai'
-import dedent from 'dedent'
 import fs from 'fs-extra'
 import path from 'path'
 import { DataContext } from '../../../src'
@@ -14,7 +13,7 @@ import {
 } from '../../../src/codegen/code-generator'
 import { SpecOptions } from '../../../src/codegen/spec-options'
 import templates from '../../../src/codegen/templates'
-import { createTestDataContext } from '../helper'
+import { createTestDataContext, dedentWithOSLineWrap } from '../helper'
 import { CT_FRAMEWORKS } from '@packages/scaffold-config'
 import { defaultSpecPattern } from '@packages/config'
 
@@ -128,7 +127,7 @@ describe('code-generator', () => {
           type: 'text',
           status: 'add',
           file: fileAbsolute,
-          content: `${dedent`
+          content: `${dedentWithOSLineWrap`
             describe('template spec', () => {
               it('passes', () => {
                 cy.visit('https://example.cypress.io')
@@ -167,7 +166,7 @@ describe('code-generator', () => {
           type: 'text',
           status: 'add',
           file: fileAbsolute,
-          content: dedent`
+          content: dedentWithOSLineWrap`
             describe('Button.tsx', () => {
               it('playground', () => {
                 // cy.mount()
@@ -208,7 +207,7 @@ describe('code-generator', () => {
           type: 'text',
           status: 'add',
           file: fileAbsolute,
-          content: dedent`import ${codeGenArgs.componentName} from '${codeGenArgs.componentPath}'
+          content: dedentWithOSLineWrap`import ${codeGenArgs.componentName} from '${codeGenArgs.componentPath}'
 
           describe('<${codeGenArgs.componentName} />', () => {
             it('renders', () => {
@@ -253,7 +252,7 @@ describe('code-generator', () => {
           type: 'text',
           status: 'add',
           file: fileAbsolute,
-          content: dedent`
+          content: dedentWithOSLineWrap`
           import React from 'react'
           import { ${codeGenArgs.componentName} } from '${codeGenArgs.componentPath}'
 
@@ -300,7 +299,7 @@ describe('code-generator', () => {
           type: 'text',
           status: 'add',
           file: fileAbsolute,
-          content: dedent`
+          content: dedentWithOSLineWrap`
           import React from 'react'
           import ${codeGenArgs.componentName} from '${codeGenArgs.componentPath}'
 
diff --git a/packages/data-context/test/unit/helper.ts b/packages/data-context/test/unit/helper.ts
index b2f5be39ec6d..e6df98f9b29f 100644
--- a/packages/data-context/test/unit/helper.ts
+++ b/packages/data-context/test/unit/helper.ts
@@ -17,6 +17,8 @@ import { remoteSchema } from '@packages/graphql/src/stitching/remoteSchema'
 import type { OpenModeOptions, RunModeOptions } from '@packages/types'
 import { MAJOR_VERSION_FOR_CONTENT } from '@packages/types'
 import { RelevantRunInfo } from '../../src/gen/graphcache-config.gen'
+import dedent from 'dedent'
+import os from 'os'
 
 type SystemTestProject = typeof fixtureDirs[number]
 type SystemTestProjectPath<T extends SystemTestProject> = `${string}/system-tests/projects/${T}`
@@ -122,3 +124,7 @@ export function createRelevantRun (runNumber: number): RelevantRunInfo {
     totalFailed: 0,
   }
 }
+
+export function dedentWithOSLineWrap (literals: string|TemplateStringsArray, ...placeholders: any[]): string {
+  return dedent(literals, ...placeholders).replace(/\n/g, os.EOL)
+}
diff --git a/packages/data-context/test/unit/sources/FileDataSource.spec.ts b/packages/data-context/test/unit/sources/FileDataSource.spec.ts
index 33503f096b6d..ccb62a9561de 100644
--- a/packages/data-context/test/unit/sources/FileDataSource.spec.ts
+++ b/packages/data-context/test/unit/sources/FileDataSource.spec.ts
@@ -42,8 +42,8 @@ describe('FileDataSource', () => {
           )
 
           expect(files).to.have.length(2)
-          expect(files[0]).to.eq(path.join(projectPath, 'root-script-1.js'))
-          expect(files[1]).to.eq(path.join(projectPath, 'root-script-2.js'))
+          expect(files[0]).to.eq(fileUtil.toPosix(path.join(projectPath, 'root-script-1.js')))
+          expect(files[1]).to.eq(fileUtil.toPosix(path.join(projectPath, 'root-script-2.js')))
         })
 
         it('finds files matching relative patterns in working dir', async () => {
@@ -67,7 +67,9 @@ describe('FileDataSource', () => {
         it('does not replace working directory in glob pattern if it is not leading', async () => {
           // Create a redundant structure within the project dir matching its absolute path
           // and write a new script in that location
-          const nestedScriptPath = path.join(projectPath, 'cypress', projectPath)
+
+          // project path on windows contains drive letter, cannot be joined directly
+          const nestedScriptPath = path.join(projectPath, 'cypress', path.parse(projectPath).base)
 
           await fs.mkdirs(nestedScriptPath)
           await fs.writeFile(path.join(nestedScriptPath, 'nested-script.js'), '')
@@ -76,7 +78,7 @@ describe('FileDataSource', () => {
           // to the working directory
           let files = await fileDataSource.getFilesByGlob(
             projectPath,
-            `./cypress${projectPath}/nested-script.js`,
+            `./cypress/${path.parse(projectPath).base}/nested-script.js`,
           )
 
           expect(files).to.have.length(1)
diff --git a/packages/data-context/test/unit/sources/ProjectDataSource.spec.ts b/packages/data-context/test/unit/sources/ProjectDataSource.spec.ts
index 110d450953ce..4f8c258ec1f5 100644
--- a/packages/data-context/test/unit/sources/ProjectDataSource.spec.ts
+++ b/packages/data-context/test/unit/sources/ProjectDataSource.spec.ts
@@ -14,6 +14,7 @@ import type { FindSpecs } from '../../../src/actions'
 import { createTestDataContext } from '../helper'
 import { defaultExcludeSpecPattern, defaultSpecPattern } from '@packages/config'
 import FixturesHelper from '@tooling/system-tests'
+import { toOS } from '../../../src/util'
 
 chai.use(sinonChai)
 const { expect } = chai
@@ -42,7 +43,7 @@ describe('matchedSpecs', () => {
         fileExtension: '.js',
         fileName: 'screenshot_element_capture_spec',
         name: 'cypress/integration/screenshot_element_capture_spec.js',
-        relative: 'cypress/integration/screenshot_element_capture_spec.js',
+        relative: toOS('cypress/integration/screenshot_element_capture_spec.js'),
         relativeToCommonRoot: 'screenshot_element_capture_spec.js',
         specFileExtension: '.js',
         specType: 'integration',
@@ -129,7 +130,7 @@ describe('transformSpec', () => {
       specType: 'integration',
       baseName: 'spec.cy.js',
       fileName: 'spec',
-      relative: 'src/spec.cy.js',
+      relative: toOS('src/spec.cy.js'),
       name: 'src/spec.cy.js',
       relativeToCommonRoot: 'C:/Windows/Project/src/spec.cy.js',
     }
@@ -265,7 +266,7 @@ describe('getLongestCommonPrefixFromPaths', () => {
       'cypress/component/bar/meta-component-test.cy.ts',
     ])
 
-    expect(lcp).to.equal('cypress/component')
+    expect(lcp).to.equal(toOS('cypress/component'))
   })
 
   it('with src and cypress', () => {
@@ -292,7 +293,7 @@ describe('getLongestCommonPrefixFromPaths', () => {
       'src/frontend/MyComponent.cy.ts',
     ])
 
-    expect(lcp).to.equal('src/frontend')
+    expect(lcp).to.equal(toOS('src/frontend'))
   })
 })
 
@@ -776,14 +777,14 @@ describe('ProjectDataSource', () => {
 
       const defaultSpecFileName = await ctx.project.defaultSpecFileName()
 
-      expect(defaultSpecFileName).to.equal('cypress/e2e/spec.cy.js')
+      expect(defaultSpecFileName).to.equal(toOS('cypress/e2e/spec.cy.js'))
     })
 
     it('yields default if the spec pattern is default', async () => {
       sinon.stub(ctx.project, 'specPatterns').resolves({ specPattern: [defaultSpecPattern.e2e] })
       const defaultSpecFileName = await ctx.project.defaultSpecFileName()
 
-      expect(defaultSpecFileName).to.equal('cypress/e2e/spec.cy.js')
+      expect(defaultSpecFileName).to.equal(toOS('cypress/e2e/spec.cy.js'))
     })
 
     it('yields common prefix if there are existing specs', async () => {
@@ -795,7 +796,7 @@ describe('ProjectDataSource', () => {
 
       const defaultSpecFileName = await ctx.project.defaultSpecFileName()
 
-      expect(defaultSpecFileName).to.equal('cypress/e2e/foo/spec.cy.js')
+      expect(defaultSpecFileName).to.equal(toOS('cypress/e2e/foo/spec.cy.js'))
     })
 
     it('yields spec pattern guess if there are no existing specs', async () => {
@@ -816,7 +817,7 @@ describe('ProjectDataSource', () => {
 
       const defaultSpecFileName = await ctx.project.defaultSpecFileName()
 
-      expect(defaultSpecFileName).to.equal('cypress/component-tests/foo/ComponentName.spec.js')
+      expect(defaultSpecFileName).to.equal(toOS('cypress/component-tests/foo/ComponentName.spec.js'))
     })
 
     describe('jsx/tsx handling', () => {
@@ -831,7 +832,7 @@ describe('ProjectDataSource', () => {
 
         const defaultSpecFileName = await ctx.project.defaultSpecFileName()
 
-        expect(defaultSpecFileName).to.equal('cypress/component/ComponentName.cy.jsx', defaultSpecFileName)
+        expect(defaultSpecFileName).to.equal(toOS('cypress/component/ComponentName.cy.jsx'), defaultSpecFileName)
       })
 
       it('yields non-jsx extension if there are jsx files but specPattern disallows', async () => {
diff --git a/packages/data-context/test/unit/util/file.spec.ts b/packages/data-context/test/unit/util/file.spec.ts
new file mode 100644
index 000000000000..f5ad70735165
--- /dev/null
+++ b/packages/data-context/test/unit/util/file.spec.ts
@@ -0,0 +1,26 @@
+import { toOS } from '../../../src/util'
+import { expect } from 'chai'
+import sinon from 'sinon'
+import path from 'path'
+
+describe('file', () => {
+  describe('#toOS', () => {
+    const posixPath = '/foo/bar/baz'
+
+    it('should convert posix path to Windows path', () => {
+      sinon.stub(path, 'sep').value('\\')
+
+      expect(toOS(posixPath)).to.equal('\\foo\\bar\\baz')
+    })
+
+    it('should return the same path if OS path separator is posix', () => {
+      sinon.stub(path, 'sep').value('/')
+
+      expect(toOS(posixPath)).to.equal(posixPath)
+    })
+
+    afterEach(() => {
+      sinon.restore()
+    })
+  })
+})