diff --git a/src/CONST.js b/src/CONST.js
index f8fbc930c9a3..33fcd8f58dad 100755
--- a/src/CONST.js
+++ b/src/CONST.js
@@ -12,8 +12,17 @@ const CONST = {
     ANDROID_PACKAGE_NAME,
     ANIMATED_TRANSITION: 300,
 
-    // 50 megabytes in bytes
-    API_MAX_ATTACHMENT_SIZE: 52428800,
+    API_ATTACHMENT_VALIDATIONS: {
+        // Same as the PHP layer allows
+        ALLOWED_EXTENSIONS: ['jpg', 'jpeg', 'png', 'gif', 'pdf', 'html', 'txt', 'rtf', 'doc', 'docx', 'htm', 'tiff', 'tif', 'xml'],
+
+        // 50 megabytes in bytes
+        MAX_SIZE: 52428800,
+
+        // An arbitrary size, but the same minimum as in the PHP layer
+        MIN_SIZE: 240,
+    },
+
     AVATAR_MAX_ATTACHMENT_SIZE: 6291456,
     NEW_EXPENSIFY_URL: ACTIVE_EXPENSIFY_URL,
     APP_DOWNLOAD_LINKS: {
diff --git a/src/components/AttachmentModal.js b/src/components/AttachmentModal.js
index 4bb62c44d0cc..b67e88f79ee3 100755
--- a/src/components/AttachmentModal.js
+++ b/src/components/AttachmentModal.js
@@ -3,7 +3,8 @@ import PropTypes from 'prop-types';
 import {View} from 'react-native';
 import Str from 'expensify-common/lib/str';
 import lodashGet from 'lodash/get';
-import _ from 'lodash';
+import lodashExtend from 'lodash/extend';
+import _ from 'underscore';
 import CONST from '../CONST';
 import Modal from './Modal';
 import AttachmentView from './AttachmentView';
@@ -71,7 +72,9 @@ class AttachmentModal extends PureComponent {
 
         this.state = {
             isModalOpen: false,
-            isConfirmModalOpen: false,
+            isAttachmentInvalid: false,
+            attachmentInvalidReasonTitle: null,
+            attachmentInvalidReason: null,
             file: null,
             sourceURL: props.sourceURL,
             modalType: CONST.MODAL.MODAL_TYPE.CENTERED_UNSWIPEABLE,
@@ -79,7 +82,7 @@ class AttachmentModal extends PureComponent {
 
         this.submitAndClose = this.submitAndClose.bind(this);
         this.closeConfirmModal = this.closeConfirmModal.bind(this);
-        this.isValidSize = this.isValidSize.bind(this);
+        this.validateAndDisplayFileToUpload = this.validateAndDisplayFileToUpload.bind(this);
     }
 
     /**
@@ -89,22 +92,30 @@ class AttachmentModal extends PureComponent {
      * @returns {String}
      */
     getModalType(sourceUrl, file) {
-        const modalType = (sourceUrl
-            && (Str.isPDF(sourceUrl) || (file && Str.isPDF(file.name || this.props.translate('attachmentView.unknownFilename')))))
+        return (
+            sourceUrl
+            && (
+                Str.isPDF(sourceUrl)
+                || (
+                    file
+                    && Str.isPDF(file.name || this.props.translate('attachmentView.unknownFilename'))
+                )
+            )
+        )
             ? CONST.MODAL.MODAL_TYPE.CENTERED_UNSWIPEABLE
             : CONST.MODAL.MODAL_TYPE.CENTERED;
-        return modalType;
     }
 
     /**
      * Returns the filename split into fileName and fileExtension
+     *
+     * @param {String} fullFileName
      * @returns {Object}
      */
-    splitExtensionFromFileName() {
-        const fullFileName = this.props.originalFileName ? this.props.originalFileName.trim() : lodashGet(this.state, 'file.name', '').trim();
-        const splittedFileName = fullFileName.split('.');
-        const fileExtension = splittedFileName.pop();
-        const fileName = splittedFileName.join('.');
+    splitExtensionFromFileName(fullFileName) {
+        const fileName = fullFileName.trim();
+        const splitFileName = fileName.split('.');
+        const fileExtension = splitFileName.pop();
         return {fileName, fileExtension};
     }
 
@@ -118,7 +129,7 @@ class AttachmentModal extends PureComponent {
         }
 
         if (this.props.onConfirm) {
-            this.props.onConfirm(_.extend(this.state.file, {source: this.state.sourceURL}));
+            this.props.onConfirm(lodashExtend(this.state.file, {source: this.state.sourceURL}));
         }
 
         this.setState({isModalOpen: false});
@@ -128,16 +139,70 @@ class AttachmentModal extends PureComponent {
      * Close the confirm modal.
      */
     closeConfirmModal() {
-        this.setState({isConfirmModalOpen: false});
+        this.setState({isAttachmentInvalid: false});
     }
 
     /**
-     * Check if the attachment size is less than the API size limit.
      * @param {Object} file
      * @returns {Boolean}
      */
-    isValidSize(file) {
-        return !file || lodashGet(file, 'size', 0) < CONST.API_MAX_ATTACHMENT_SIZE;
+    isValidFile(file) {
+        if (lodashGet(file, 'size', 0) > CONST.API_ATTACHMENT_VALIDATIONS.MAX_SIZE) {
+            this.setState({
+                isAttachmentInvalid: true,
+                attachmentInvalidReasonTitle: this.props.translate('attachmentPicker.attachmentTooLarge'),
+                attachmentInvalidReason: this.props.translate('attachmentPicker.sizeExceeded'),
+            });
+            return false;
+        }
+
+        if (lodashGet(file, 'size', 0) < CONST.API_ATTACHMENT_VALIDATIONS.MIN_SIZE) {
+            this.setState({
+                isAttachmentInvalid: true,
+                attachmentInvalidReasonTitle: this.props.translate('attachmentPicker.attachmentTooSmall'),
+                attachmentInvalidReason: this.props.translate('attachmentPicker.sizeNotMet'),
+            });
+            return false;
+        }
+
+        const {fileExtension} = this.splitExtensionFromFileName(lodashGet(file, 'name', ''));
+        if (!_.contains(CONST.API_ATTACHMENT_VALIDATIONS.ALLOWED_EXTENSIONS, fileExtension)) {
+            const invalidReason = `${this.props.translate('attachmentPicker.notAllowedExtension')} ${CONST.API_ATTACHMENT_VALIDATIONS.ALLOWED_EXTENSIONS.join(', ')}`;
+            this.setState({
+                isAttachmentInvalid: true,
+                attachmentInvalidReasonTitle: this.props.translate('attachmentPicker.wrongFileType'),
+                attachmentInvalidReason: invalidReason,
+            });
+            return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * @param {Object} file
+     */
+    validateAndDisplayFileToUpload(file) {
+        if (!file) {
+            return;
+        }
+
+        if (!this.isValidFile(file)) {
+            return;
+        }
+
+        if (file instanceof File) {
+            const source = URL.createObjectURL(file);
+            const modalType = this.getModalType(source, file);
+            this.setState({
+                isModalOpen: true, sourceURL: source, file, modalType,
+            });
+        } else {
+            const modalType = this.getModalType(file.uri, file);
+            this.setState({
+                isModalOpen: true, sourceURL: file.uri, file, modalType,
+            });
+        }
     }
 
     render() {
@@ -149,7 +214,7 @@ class AttachmentModal extends PureComponent {
             ? [styles.imageModalImageCenterContainer]
             : [styles.imageModalImageCenterContainer, styles.p5];
 
-        const {fileName, fileExtension} = this.splitExtensionFromFileName();
+        const {fileName, fileExtension} = this.splitExtensionFromFileName(this.props.originalFileName || lodashGet(this.state, 'file.name', ''));
 
         return (
             <>
@@ -197,34 +262,19 @@ class AttachmentModal extends PureComponent {
                         />
                     )}
                 </Modal>
+
                 <ConfirmModal
-                    title={this.props.translate('attachmentPicker.attachmentTooLarge')}
+                    title={this.state.attachmentInvalidReasonTitle}
                     onConfirm={this.closeConfirmModal}
                     onCancel={this.closeConfirmModal}
-                    isVisible={this.state.isConfirmModalOpen}
-                    prompt={this.props.translate('attachmentPicker.sizeExceeded')}
+                    isVisible={this.state.isAttachmentInvalid}
+                    prompt={this.state.attachmentInvalidReason}
                     confirmText={this.props.translate('common.close')}
                     shouldShowCancelButton={false}
                 />
+
                 {this.props.children({
-                    displayFileInModal: ({file}) => {
-                        if (!this.isValidSize(file)) {
-                            this.setState({isConfirmModalOpen: true});
-                            return;
-                        }
-                        if (file instanceof File) {
-                            const source = URL.createObjectURL(file);
-                            const modalType = this.getModalType(source, file);
-                            this.setState({
-                                isModalOpen: true, sourceURL: source, file, modalType,
-                            });
-                        } else {
-                            const modalType = this.getModalType(file.uri, file);
-                            this.setState({
-                                isModalOpen: true, sourceURL: file.uri, file, modalType,
-                            });
-                        }
-                    },
+                    displayFileInModal: this.validateAndDisplayFileToUpload,
                     show: () => {
                         this.setState({isModalOpen: true});
                     },
diff --git a/src/components/ConfirmModal.js b/src/components/ConfirmModal.js
index 5c89135bef7b..bf7d1e2fffda 100755
--- a/src/components/ConfirmModal.js
+++ b/src/components/ConfirmModal.js
@@ -7,7 +7,7 @@ import ConfirmContent from './ConfirmContent';
 
 const propTypes = {
     /** Title of the modal */
-    title: PropTypes.string.isRequired,
+    title: PropTypes.string,
 
     /** A callback to call when the form has been submitted */
     onConfirm: PropTypes.func.isRequired,
@@ -54,6 +54,7 @@ const defaultProps = {
     onCancel: () => {},
     shouldShowCancelButton: true,
     shouldSetModalVisibility: true,
+    title: '',
     onModalHide: () => {},
 };
 
diff --git a/src/languages/en.js b/src/languages/en.js
index fa86c37a450d..4cb0a8029e92 100755
--- a/src/languages/en.js
+++ b/src/languages/en.js
@@ -119,6 +119,10 @@ export default {
         chooseDocument: 'Choose document',
         attachmentTooLarge: 'Attachment too large',
         sizeExceeded: 'Attachment size is larger than 50 MB limit.',
+        attachmentTooSmall: 'Attachment too small',
+        sizeNotMet: 'Attachment size must be greater than 240 bytes',
+        wrongFileType: 'Attachment is the wrong type',
+        notAllowedExtension: 'Attachments must be one of the following types: ',
     },
     composer: {
         noExtentionFoundForMimeType: 'No extension found for mime type',
diff --git a/src/languages/es.js b/src/languages/es.js
index 934df4f03e1c..661c1793c6b1 100644
--- a/src/languages/es.js
+++ b/src/languages/es.js
@@ -119,6 +119,10 @@ export default {
         chooseDocument: 'Elegir documento',
         attachmentTooLarge: 'Archivo adjunto demasiado grande',
         sizeExceeded: 'El archivo adjunto supera el límite de 50 MB.',
+        attachmentTooSmall: 'Archivo adjunto demasiado pequeño',
+        sizeNotMet: 'El archivo adjunto debe ser mas grande que 240 bytes',
+        wrongFileType: 'El tipo del archivo adjunto es incorrecto',
+        notAllowedExtension: 'Los archivos adjuntos deben ser de uno de los siguientes tipos: ',
     },
     composer: {
         noExtentionFoundForMimeType: 'No se encontró una extension para este tipo de contenido',
diff --git a/src/libs/actions/User.js b/src/libs/actions/User.js
index 2565c4575997..4f22eb497350 100644
--- a/src/libs/actions/User.js
+++ b/src/libs/actions/User.js
@@ -241,19 +241,19 @@ function validateLogin(accountID, validateCode) {
  * Checks the blockedFromConcierge object to see if it has an expiresAt key,
  * and if so whether the expiresAt date of a user's ban is before right now
  *
- * @param {Object} blockedFromConcierge
+ * @param {Object} blockedFromConciergeNVP
  * @returns {Boolean}
  */
-function isBlockedFromConcierge(blockedFromConcierge) {
-    if (_.isEmpty(blockedFromConcierge)) {
+function isBlockedFromConcierge(blockedFromConciergeNVP) {
+    if (_.isEmpty(blockedFromConciergeNVP)) {
         return false;
     }
 
-    if (!blockedFromConcierge.expiresAt) {
+    if (!blockedFromConciergeNVP.expiresAt) {
         return false;
     }
 
-    return moment().isBefore(moment(blockedFromConcierge.expiresAt), 'day');
+    return moment().isBefore(moment(blockedFromConciergeNVP.expiresAt), 'day');
 }
 
 /**
diff --git a/src/pages/home/report/ReportActionCompose.js b/src/pages/home/report/ReportActionCompose.js
index fd45bd61626b..6e58ae1f5715 100755
--- a/src/pages/home/report/ReportActionCompose.js
+++ b/src/pages/home/report/ReportActionCompose.js
@@ -124,12 +124,14 @@ class ReportActionCompose extends React.Component {
         this.setIsFullComposerAvailable = this.setIsFullComposerAvailable.bind(this);
         this.focus = this.focus.bind(this);
         this.addEmojiToTextBox = this.addEmojiToTextBox.bind(this);
-        this.comment = props.comment;
-        this.shouldFocusInputOnScreenFocus = canFocusInputOnScreenFocus();
         this.onSelectionChange = this.onSelectionChange.bind(this);
         this.setTextInputRef = this.setTextInputRef.bind(this);
         this.getInputPlaceholder = this.getInputPlaceholder.bind(this);
         this.getIOUOptions = this.getIOUOptions.bind(this);
+        this.addAttachment = this.addAttachment.bind(this);
+
+        this.comment = props.comment;
+        this.shouldFocusInputOnScreenFocus = canFocusInputOnScreenFocus();
 
         this.state = {
             isFocused: this.shouldFocusInputOnScreenFocus,
@@ -447,6 +449,15 @@ class ReportActionCompose extends React.Component {
         return trimmedComment;
     }
 
+    /**
+     * @param {Object} file
+     */
+    addAttachment(file) {
+        const comment = this.prepareCommentAndResetComposer();
+        Report.addAttachment(this.props.reportID, file, comment);
+        this.setTextInputShouldClear(false);
+    }
+
     /**
      * Add a new comment to this chat
      *
@@ -500,11 +511,7 @@ class ReportActionCompose extends React.Component {
                 >
                     <AttachmentModal
                         headerTitle={this.props.translate('reportActionCompose.sendAttachment')}
-                        onConfirm={(file) => {
-                            const comment = this.prepareCommentAndResetComposer();
-                            Report.addAttachment(this.props.reportID, file, comment);
-                            this.setTextInputShouldClear(false);
-                        }}
+                        onConfirm={this.addAttachment}
                     >
                         {({displayFileInModal}) => (
                             <>
@@ -572,9 +579,7 @@ class ReportActionCompose extends React.Component {
                                                         text: this.props.translate('reportActionCompose.addAttachment'),
                                                         onSelected: () => {
                                                             openPicker({
-                                                                onPicked: (file) => {
-                                                                    displayFileInModal({file});
-                                                                },
+                                                                onPicked: displayFileInModal,
                                                             });
                                                         },
                                                     },
@@ -616,7 +621,7 @@ class ReportActionCompose extends React.Component {
                                                 return;
                                             }
 
-                                            displayFileInModal({file});
+                                            displayFileInModal(file);
                                             this.setState({isDraggingOver: false});
                                         }}
                                         style={[styles.textInputCompose, this.props.isComposerFullSize ? styles.textInputFullCompose : styles.flex4]}
@@ -624,7 +629,7 @@ class ReportActionCompose extends React.Component {
                                         maxLines={this.state.maxLines}
                                         onFocus={() => this.setIsFocused(true)}
                                         onBlur={() => this.setIsFocused(false)}
-                                        onPasteFile={file => displayFileInModal({file})}
+                                        onPasteFile={displayFileInModal}
                                         shouldClear={this.state.textInputShouldClear}
                                         onClear={() => this.setTextInputShouldClear(false)}
                                         isDisabled={isComposeDisabled || isBlockedFromConcierge}
diff --git a/src/pages/home/report/ReportActionItem.js b/src/pages/home/report/ReportActionItem.js
index 10e5b58de3cb..f36440dcabaf 100644
--- a/src/pages/home/report/ReportActionItem.js
+++ b/src/pages/home/report/ReportActionItem.js
@@ -28,6 +28,8 @@ import {withNetwork, withReportActionsDrafts} from '../../../components/OnyxProv
 import RenameAction from '../../../components/ReportActionItem/RenameAction';
 import InlineSystemMessage from '../../../components/InlineSystemMessage';
 import styles from '../../../styles/styles';
+import * as User from '../../../libs/actions/User';
+import * as ReportUtils from '../../../libs/ReportUtils';
 
 const propTypes = {
     /** The ID of the report this action is on. */
@@ -139,16 +141,20 @@ class ReportActionItem extends Component {
             );
         } else {
             children = !this.props.draftMessage
-                ? <ReportActionItemMessage action={this.props.action} />
-                : (
+                ? (
+                    <ReportActionItemMessage action={this.props.action} />
+                ) : (
                     <ReportActionItemMessageEdit
-                            action={this.props.action}
-                            draftMessage={this.props.draftMessage}
-                            reportID={this.props.reportID}
-                            index={this.props.index}
-                            ref={el => this.textInput = el}
-                            report={this.props.report}
-                            blockedFromConcierge={this.props.blockedFromConcierge}
+                        action={this.props.action}
+                        draftMessage={this.props.draftMessage}
+                        reportID={this.props.reportID}
+                        index={this.props.index}
+                        ref={el => this.textInput = el}
+                        report={this.props.report}
+                        shouldDisableEmojiPicker={
+                            (ReportUtils.chatIncludesConcierge(this.props.report) && User.isBlockedFromConcierge(this.props.blockedFromConcierge))
+                            || ReportUtils.isArchivedRoom(this.props.report)
+                        }
                     />
                 );
         }
diff --git a/src/pages/home/report/ReportActionItemMessageEdit.js b/src/pages/home/report/ReportActionItemMessageEdit.js
index c2b270c9085a..3e64cfaaf09c 100644
--- a/src/pages/home/report/ReportActionItemMessageEdit.js
+++ b/src/pages/home/report/ReportActionItemMessageEdit.js
@@ -16,10 +16,8 @@ import Button from '../../../components/Button';
 import ReportActionComposeFocusManager from '../../../libs/ReportActionComposeFocusManager';
 import compose from '../../../libs/compose';
 import EmojiPickerButton from '../../../components/EmojiPicker/EmojiPickerButton';
-import * as ReportUtils from '../../../libs/ReportUtils';
 import * as ReportActionContextMenu from './ContextMenu/ReportActionContextMenu';
 import VirtualKeyboard from '../../../libs/VirtualKeyboard';
-import * as User from '../../../libs/actions/User';
 
 const propTypes = {
     /** All the data of the action */
@@ -43,11 +41,8 @@ const propTypes = {
         participants: PropTypes.arrayOf(PropTypes.string),
     }),
 
-    // The NVP describing a user's block status
-    blockedFromConcierge: PropTypes.shape({
-        // The date that the user will be unblocked
-        expiresAt: PropTypes.string,
-    }),
+    // Whether or not the emoji picker is disabled
+    shouldDisableEmojiPicker: PropTypes.bool,
 
     /** Window Dimensions Props */
     ...windowDimensionsPropTypes,
@@ -59,7 +54,7 @@ const propTypes = {
 const defaultProps = {
     forwardedRef: () => {},
     report: {},
-    blockedFromConcierge: {},
+    shouldDisableEmojiPicker: false,
 };
 
 class ReportActionItemMessageEdit extends React.Component {
@@ -190,10 +185,6 @@ class ReportActionItemMessageEdit extends React.Component {
     }
 
     render() {
-        const shouldDisableEmojiPicker = (ReportUtils.chatIncludesConcierge(this.props.report)
-                                            && User.isBlockedFromConcierge(this.props.blockedFromConcierge))
-                                            || ReportUtils.isArchivedRoom(this.props.report);
-
         return (
             <View style={styles.chatItemMessage}>
                 <View style={[styles.chatItemComposeBox, styles.flexRow, styles.chatItemComposeBoxColor]}>
@@ -225,7 +216,7 @@ class ReportActionItemMessageEdit extends React.Component {
                     />
                     <View style={styles.editChatItemEmojiWrapper}>
                         <EmojiPickerButton
-                            isDisabled={shouldDisableEmojiPicker}
+                            isDisabled={this.props.shouldDisableEmojiPicker}
                             onModalHide={() => InteractionManager.runAfterInteractions(() => this.textInput.focus())}
                             onEmojiSelected={this.addEmojiToTextBox}
                         />