Improve app initialisation for timeouts (#1412)

Fixes: #1510 

Co-authored-by: Arpit Mohan <mohanarpit@users.noreply.github.com>

app/client/src/actions/applicationActions.ts

@@ -1,5 +1,4 @@
 import { ReduxAction, ReduxActionTypes } from "constants/ReduxActionConstants";
-import { EditorModes } from "../components/editorComponents/CodeEditor/EditorConfig";
 import { APP_MODE } from "../reducers/entityReducers/appReducer";
 import { UpdateApplicationPayload } from "api/ApplicationApi";
 

app/client/src/actions/initActions.ts

@@ -2,6 +2,7 @@ import {
   ReduxActionTypes,
   ReduxAction,
   InitializeEditorPayload,
+  ReduxActionErrorTypes,
 } from "constants/ReduxActionConstants";
 
 export const initEditor = (
@@ -14,3 +15,17 @@ export const initEditor = (
     pageId,
   },
 });
+
+export const initEditorError = (): ReduxAction<{ show: false }> => ({
+  type: ReduxActionErrorTypes.INITIALIZE_EDITOR_ERROR,
+  payload: {
+    show: false,
+  },
+});
+
+export const initViewerError = (): ReduxAction<{ show: false }> => ({
+  type: ReduxActionErrorTypes.INITIALIZE_PAGE_VIEWER_ERROR,
+  payload: {
+    show: false,
+  },
+});

app/client/src/api/Api.tsx

@@ -4,13 +4,10 @@ import {
   API_REQUEST_HEADERS,
 } from "constants/ApiConstants";
 import { ActionApiResponse } from "./ActionAPI";
-import {
-  AUTH_LOGIN_URL,
-  PAGE_NOT_FOUND_URL,
-  SERVER_ERROR_URL,
-} from "constants/routes";
+import { AUTH_LOGIN_URL, PAGE_NOT_FOUND_URL } from "constants/routes";
 import history from "utils/history";
 import { convertObjectToQueryParams } from "utils/AppsmithUtils";
+import { SERVER_API_TIMEOUT_ERROR } from "../constants/messages";
 
 //TODO(abhinav): Refactor this to make more composable.
 export const apiRequestConfig = {
@@ -22,8 +19,10 @@ export const apiRequestConfig = {
 
 const axiosInstance: AxiosInstance = axios.create();
 
+export const axiosConnectionAbortedCode = "ECONNABORTED";
 const executeActionRegex = /actions\/execute/;
-const currentUserRegex = /\/me$/;
+const timeoutErrorRegex = /timeout of (\d+)ms exceeded/;
+
 axiosInstance.interceptors.request.use((config: any) => {
   return { ...config, timer: performance.now() };
 });
@@ -50,20 +49,25 @@ axiosInstance.interceptors.response.use(
     return response.data;
   },
   function(error: any) {
+    // Return if the call was cancelled via cancel token
     if (axios.isCancel(error)) {
       return;
     }
-    if (error.code === "ECONNABORTED") {
-      if (error.config && error.config.url.match(currentUserRegex)) {
-        history.replace({ pathname: SERVER_ERROR_URL });
-      }
-      return Promise.reject({
-        message: "Please check your internet connection",
-      });
-    }
+    // Return modified response if action execution failed
     if (error.config && error.config.url.match(executeActionRegex)) {
       return makeExecuteActionResponse(error.response);
     }
+    // Return error if any timeout happened in other api calls
+    if (
+      error.code === axiosConnectionAbortedCode &&
+      error.message &&
+      error.message.match(timeoutErrorRegex)
+    ) {
+      return Promise.reject({
+        ...error,
+        message: SERVER_API_TIMEOUT_ERROR,
+      });
+    }
     if (error.response) {
       // The request was made and the server responded with a status code
       // that falls out of the range of 2xx

app/client/src/constants/AppConstants.ts

@@ -8,3 +8,20 @@ const APP_STORE_NAMESPACE = "APPSMITH_LOCAL_STORE";
 
 export const getAppStoreName = (appId: string) =>
   `${APP_STORE_NAMESPACE}-${appId}`;
+
+export const getAppStore = (appId: string) => {
+  const appStoreName = getAppStoreName(appId);
+  let storeString = "{}";
+  // Check if localStorage exists
+  if (localStorage) {
+    const appStore = localStorage.getItem(appStoreName);
+    if (appStore) storeString = appStore;
+  }
+  let store;
+  try {
+    store = JSON.parse(storeString);
+  } catch (e) {
+    store = {};
+  }
+  return store;
+};

app/client/src/constants/ReduxActionConstants.tsx

@@ -296,6 +296,7 @@ export type ReduxActionType = typeof ReduxActionTypes[keyof typeof ReduxActionTy
 
 export const ReduxActionErrorTypes: { [key: string]: string } = {
   INITIALIZE_EDITOR_ERROR: "INITIALIZE_EDITOR_ERROR",
+  INITIALIZE_PAGE_VIEWER_ERROR: "INITIALIZE_PAGE_VIEWER_ERROR",
   API_ERROR: "API_ERROR",
   WIDGET_DELETE_ERROR: "WIDGET_DELETE_ERROR",
   UPDATE_APPLICATION_ERROR: "UPDATE_APPLICATION_ERROR",

app/client/src/constants/messages.ts

@@ -168,3 +168,6 @@ export const GOOGLE_RECAPTCHA_KEY_ERROR =
   "Google Re-Captcha Token Generation failed! Please check the Re-captcha Site Key.";
 export const GOOGLE_RECAPTCHA_DOMAIN_ERROR =
   "Google Re-Captcha Token Generation failed! Please check the allowed domains.";
+
+export const SERVER_API_TIMEOUT_ERROR =
+  "Appsmith server is taking too long to respond. Please try again after some time";

app/client/src/pages/AppViewer/index.tsx

@@ -10,7 +10,10 @@ import {
   getApplicationViewerPageURL,
 } from "constants/routes";
 import { ReduxActionTypes } from "constants/ReduxActionConstants";
-import { getIsInitialized } from "selectors/appViewSelectors";
+import {
+  getIsInitialized,
+  getIsInitializeError,
+} from "selectors/appViewSelectors";
 import { executeAction } from "actions/widgetActions";
 import { ExecuteActionPayload } from "constants/ActionConstants";
 import { updateWidgetPropertyRequest } from "actions/controlActions";
@@ -23,6 +26,8 @@ import {
 } from "actions/metaActions";
 import { editorInitializer } from "utils/EditorUtils";
 import * as Sentry from "@sentry/react";
+import log from "loglevel";
+import ServerTimeout from "../common/ServerTimeout";
 const SentryRoute = Sentry.withSentryRouting(Route);
 
 const AppViewerBody = styled.section`
@@ -36,6 +41,7 @@ const AppViewerBody = styled.section`
 export type AppViewerProps = {
   initializeAppViewer: (applicationId: string, pageId?: string) => void;
   isInitialized: boolean;
+  isInitializeError: boolean;
   executeAction: (actionPayload: ExecuteActionPayload) => void;
   updateWidgetProperty: (
     widgetId: string,
@@ -62,7 +68,7 @@ class AppViewer extends Component<
       this.setState({ registered: true });
     });
     const { applicationId, pageId } = this.props.match.params;
-    console.log({ applicationId, pageId });
+    log.debug({ applicationId, pageId });
     if (applicationId) {
       this.props.initializeAppViewer(applicationId, pageId);
     }
@@ -73,7 +79,10 @@ class AppViewer extends Component<
   };
 
   public render() {
-    const { isInitialized } = this.props;
+    const { isInitialized, isInitializeError } = this.props;
+    if (isInitializeError) {
+      return <ServerTimeout />;
+    }
     return (
       <EditorContext.Provider
         value={{
@@ -100,6 +109,7 @@ class AppViewer extends Component<
 
 const mapStateToProps = (state: AppState) => ({
   isInitialized: getIsInitialized(state),
+  isInitializeError: getIsInitializeError(state),
 });
 
 const mapDispatchToProps = (dispatch: any) => ({

app/client/src/pages/Editor/index.tsx

@@ -1,7 +1,7 @@
 import React, { Component } from "react";
 import { Helmet } from "react-helmet";
 import { connect } from "react-redux";
-import { withRouter, RouteComponentProps } from "react-router-dom";
+import { RouteComponentProps, withRouter } from "react-router-dom";
 import {
   BuilderRouteParams,
   getApplicationViewerPageURL,
@@ -13,15 +13,16 @@ import TouchBackend from "react-dnd-touch-backend";
 import {
   getCurrentApplicationId,
   getCurrentPageId,
-  getPublishingError,
-  getIsEditorLoading,
   getIsEditorInitialized,
+  getIsEditorInitializeError,
+  getIsEditorLoading,
   getIsPublishingApplication,
+  getPublishingError,
 } from "selectors/editorSelectors";
 import {
-  Dialog,
-  Classes,
   AnchorButton,
+  Classes,
+  Dialog,
   Hotkey,
   Hotkeys,
   Spinner,
@@ -40,11 +41,12 @@ import ConfirmRunModal from "pages/Editor/ConfirmRunModal";
 import * as Sentry from "@sentry/react";
 import {
   copyWidget,
-  pasteWidget,
-  deleteSelectedWidget,
   cutWidget,
+  deleteSelectedWidget,
+  pasteWidget,
 } from "actions/widgetActions";
 import { isMac } from "utils/helpers";
+import ServerTimeout from "../common/ServerTimeout";
 
 type EditorProps = {
   currentApplicationId?: string;
@@ -53,6 +55,7 @@ type EditorProps = {
   isPublishing: boolean;
   isEditorLoading: boolean;
   isEditorInitialized: boolean;
+  isEditorInitializeError: boolean;
   errorPublishing: boolean;
   copySelectedWidget: () => void;
   pasteCopiedWidget: () => void;
@@ -189,6 +192,8 @@ class Editor extends Component<Props> {
       nextProps.isPublishing !== this.props.isPublishing ||
       nextProps.isEditorLoading !== this.props.isEditorLoading ||
       nextProps.errorPublishing !== this.props.errorPublishing ||
+      nextProps.isEditorInitializeError !==
+        this.props.isEditorInitializeError ||
       nextState.isDialogOpen !== this.state.isDialogOpen ||
       nextState.registered !== this.state.registered
     );
@@ -200,6 +205,9 @@ class Editor extends Component<Props> {
     });
   };
   public render() {
+    if (this.props.isEditorInitializeError) {
+      return <ServerTimeout />;
+    }
     if (!this.props.isEditorInitialized || !this.state.registered) {
       return (
         <CenteredWrapper style={{ height: "calc(100vh - 48px)" }}>
@@ -260,6 +268,7 @@ const mapStateToProps = (state: AppState) => ({
   isPublishing: getIsPublishingApplication(state),
   isEditorLoading: getIsEditorLoading(state),
   isEditorInitialized: getIsEditorInitialized(state),
+  isEditorInitializeError: getIsEditorInitializeError(state),
   user: getCurrentUser(state),
 });
 

app/client/src/pages/common/PageNotFound.tsx

@@ -1,5 +1,5 @@
 import React from "react";
-import { RouterProps } from "react-router";
+import { RouteComponentProps, withRouter } from "react-router";
 import styled from "styled-components";
 import Button from "components/editorComponents/Button";
 import PageUnavailableImage from "assets/images/404-image.png";
@@ -20,7 +20,7 @@ const Wrapper = styled.div`
   }
 `;
 
-class PageNotFound extends React.PureComponent<RouterProps> {
+class PageNotFound extends React.PureComponent<RouteComponentProps> {
   public render() {
     return (
       <>
@@ -54,4 +54,4 @@ class PageNotFound extends React.PureComponent<RouterProps> {
   }
 }
 
-export default PageNotFound;
+export default withRouter(PageNotFound);

app/client/src/pages/common/ServerTimeout.tsx

@@ -0,0 +1,56 @@
+import React from "react";
+import styled from "styled-components";
+import AppTimeoutImage from "assets/images/timeout-image.png";
+
+const Wrapper = styled.div`
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  text-align: center;
+  height: calc(100vh - ${props => props.theme.headerHeight});
+  .bold-text {
+    font-weight: ${props => props.theme.fontWeights[3]};
+    font-size: 24px;
+  }
+  .page-unavailable-img {
+    width: 35%;
+  }
+  .button-position {
+    margin: auto;
+  }
+`;
+
+const RetryButton = styled.button`
+  background-color: #f3672a;
+  color: white;
+  height: 40px;
+  width: 300px;
+  border: none;
+  cursor: pointer;
+  font-weight: 600;
+  font-size: 17px;
+`;
+
+const ServerTimeout = () => {
+  return (
+    <Wrapper>
+      <img
+        src={AppTimeoutImage}
+        alt="Page Unavailable"
+        className="page-unavailable-img"
+      />
+      <div>
+        <p className="bold-text">
+          Appsmith server is taking too long to respond
+        </p>
+        <p>Please retry after some time</p>
+        <RetryButton onClick={() => window.location.reload()}>
+          {"Retry"}
+        </RetryButton>
+      </div>
+    </Wrapper>
+  );
+};
+
+export default ServerTimeout;

app/client/src/reducers/uiReducers/appViewReducer.tsx

@@ -5,12 +5,14 @@ import {
   ReduxAction,
   ReduxActionTypes,
   PageListPayload,
+  ReduxActionErrorTypes,
 } from "constants/ReduxActionConstants";
 import { FetchPublishedPageSuccessPayload } from "actions/pageActions";
 
 const initialState: AppViewReduxState = {
   isFetchingPage: false,
   initialized: false,
+  initializeError: false,
   pages: [],
   pageWidgetId: "0",
 };
@@ -24,6 +26,11 @@ const appViewReducer = createReducer(initialState, {
   ) => {
     return { ...state, initialized: true };
   },
+  [ReduxActionErrorTypes.INITIALIZE_PAGE_VIEWER_ERROR]: (
+    state: AppViewReduxState,
+  ) => {
+    return { ...state, initializeError: true };
+  },
   [ReduxActionTypes.FETCH_PUBLISHED_PAGE_INIT]: (state: AppViewReduxState) => {
     return { ...state, dsl: undefined, isFetchingPage: true };
   },
@@ -45,6 +52,7 @@ const appViewReducer = createReducer(initialState, {
 
 export interface AppViewReduxState {
   initialized: boolean;
+  initializeError: boolean;
   dsl?: ContainerWidgetProps<WidgetProps>;
   isFetchingPage: boolean;
   currentLayoutId?: string;

app/client/src/reducers/uiReducers/editorReducer.tsx

@@ -5,12 +5,11 @@ import {
   ReduxActionTypes,
   ReduxActionErrorTypes,
 } from "constants/ReduxActionConstants";
-import { WidgetProps } from "widgets/BaseWidget";
-import { ContainerWidgetProps } from "widgets/ContainerWidget";
 import moment from "moment";
 
 const initialState: EditorReduxState = {
   initialized: false,
+  initializationError: false,
   loadingStates: {
     publishing: false,
     publishingError: false,
@@ -68,11 +67,8 @@ const editorReducer = createReducer(initialState, {
   ) => {
     return {
       ...state,
-      loadingStates: {
-        ...state.loadingStates,
-        loading: false,
-        loadingError: true,
-      },
+      initializationError: true,
+      initialized: false,
     };
   },
   [ReduxActionTypes.PUBLISH_APPLICATION_INIT]: (state: EditorReduxState) => {
@@ -178,7 +174,7 @@ const editorReducer = createReducer(initialState, {
 
 export interface EditorReduxState {
   initialized: boolean;
-  dsl?: ContainerWidgetProps<WidgetProps>;
+  initializationError: boolean;
   pageWidgetId?: string;
   currentLayoutId?: string;
   currentPageName?: string;

app/client/src/sagas/ErrorSagas.tsx

@@ -11,6 +11,7 @@ import { put, takeLatest, call } from "redux-saga/effects";
 import { ERROR_401, ERROR_500, ERROR_0 } from "constants/messages";
 import { ToastType } from "react-toastify";
 import log from "loglevel";
+import { axiosConnectionAbortedCode } from "../api/Api";
 
 export function* callAPI(apiCall: any, requestPayload: any) {
   try {
@@ -60,7 +61,7 @@ export function getResponseErrorMessage(response: ApiResponse) {
     : undefined;
 }
 
-type ErrorPayloadType = { code?: number; message?: string };
+type ErrorPayloadType = { code?: number | string; message?: string };
 let ActionErrorDisplayMap: {
   [key: string]: (error: ErrorPayloadType) => string;
 } = {};
@@ -92,6 +93,7 @@ export function* errorSaga(
     type,
     payload: { error, show = true },
   } = errorAction;
+
   const message =
     error && error.message ? error.message : ActionErrorDisplayMap[type](error);
 

app/client/src/sagas/InitSagas.ts

@@ -1,7 +1,14 @@
-import { all, call, put, select, take, takeLatest } from "redux-saga/effects";
+import {
+  all,
+  call,
+  put,
+  select,
+  take,
+  takeLatest,
+  race,
+} from "redux-saga/effects";
 import {
   InitializeEditorPayload,
-  Page,
   ReduxAction,
   ReduxActionErrorTypes,
   ReduxActionTypes,
@@ -21,126 +28,86 @@ import { fetchActions, fetchActionsForView } from "actions/actionActions";
 import { fetchApplication } from "actions/applicationActions";
 import AnalyticsUtil from "utils/AnalyticsUtil";
 import { getCurrentApplication } from "selectors/applicationSelectors";
-import { AppState } from "reducers";
-import PageApi, { FetchPageResponse } from "api/PageApi";
-import { validateResponse } from "./ErrorSagas";
-import { extractCurrentDSL } from "utils/WidgetPropsUtils";
 import { APP_MODE } from "reducers/entityReducers/appReducer";
-import { getAppStoreName } from "constants/AppConstants";
+import { getAppStore } from "constants/AppConstants";
 import { getDefaultPageId } from "./selectors";
-
-const getAppStore = (appId: string) => {
-  const appStoreName = getAppStoreName(appId);
-  const storeString = localStorage.getItem(appStoreName) || "{}";
-  let store;
-  try {
-    store = JSON.parse(storeString);
-  } catch (e) {
-    store = {};
-  }
-  return store;
-};
+import { populatePageDSLsSaga } from "./PageSagas";
+import { initEditorError, initViewerError } from "../actions/initActions";
 
 function* initializeEditorSaga(
   initializeEditorAction: ReduxAction<InitializeEditorPayload>,
 ) {
   const { applicationId, pageId } = initializeEditorAction.payload;
-  // Step 1: Set App Mode. Start getting all the data needed
-  yield put(setAppMode(APP_MODE.EDIT));
-  yield put({ type: ReduxActionTypes.START_EVALUATION });
-  yield all([
-    put(fetchPageList(applicationId, APP_MODE.EDIT)),
-    put(fetchEditorConfigs()),
-    put(fetchActions(applicationId)),
-    put(fetchPage(pageId)),
-    put(fetchApplication(applicationId, APP_MODE.EDIT)),
-  ]);
-  // Step 2: Wait for all data to be in the state
-  yield all([
-    take(ReduxActionTypes.FETCH_PAGE_LIST_SUCCESS),
-    take(ReduxActionTypes.FETCH_PAGE_SUCCESS),
-    take(ReduxActionTypes.SWITCH_CURRENT_PAGE_ID),
-    take(ReduxActionTypes.FETCH_ACTIONS_SUCCESS),
-  ]);
-
-  // Step 3: Call all the APIs which needs Organization Id from PageList API response.
-  yield all([put(fetchPlugins()), put(fetchDatasources())]);
-
-  // Step 4: Wait for all data to be in the state
-  yield all([
-    take(ReduxActionTypes.FETCH_PLUGINS_SUCCESS),
-    take(ReduxActionTypes.FETCH_DATASOURCES_SUCCESS),
-  ]);
-
-  // Step 5: Set app store
-  yield put(updateAppStore(getAppStore(applicationId)));
-
-  const currentApplication = yield select(getCurrentApplication);
-
-  const appName = currentApplication ? currentApplication.name : "";
-  const appId = currentApplication ? currentApplication.id : "";
-
-  AnalyticsUtil.logEvent("EDITOR_OPEN", {
-    appId: appId,
-    appName: appName,
-  });
-
-  // Step 6: Notify UI that the editor is ready to go
-  yield put({
-    type: ReduxActionTypes.INITIALIZE_EDITOR_SUCCESS,
-  });
-  yield call(populatePageDSLsSaga);
-}
-
-function* fetchPageDSLSaga(pageId: string) {
   try {
-    const fetchPageResponse: FetchPageResponse = yield call(PageApi.fetchPage, {
-      id: pageId,
+    yield put(setAppMode(APP_MODE.EDIT));
+    yield put({ type: ReduxActionTypes.START_EVALUATION });
+    yield all([
+      put(fetchPageList(applicationId, APP_MODE.EDIT)),
+      put(fetchEditorConfigs()),
+      put(fetchActions(applicationId)),
+      put(fetchPage(pageId)),
+      put(fetchApplication(applicationId, APP_MODE.EDIT)),
+    ]);
+
+    const resultOfPrimaryCalls = yield race({
+      success: all([
+        take(ReduxActionTypes.FETCH_PAGE_LIST_SUCCESS),
+        take(ReduxActionTypes.FETCH_PAGE_SUCCESS),
+        take(ReduxActionTypes.FETCH_APPLICATION_SUCCESS),
+        take(ReduxActionTypes.FETCH_ACTIONS_SUCCESS),
+      ]),
+      failure: take([
+        ReduxActionErrorTypes.FETCH_PAGE_LIST_ERROR,
+        ReduxActionErrorTypes.FETCH_PAGE_ERROR,
+        ReduxActionErrorTypes.FETCH_APPLICATION_ERROR,
+        ReduxActionErrorTypes.FETCH_ACTIONS_ERROR,
+      ]),
     });
-    const isValidResponse = yield validateResponse(fetchPageResponse);
-    if (isValidResponse) {
-      return {
-        pageId: pageId,
-        dsl: extractCurrentDSL(fetchPageResponse),
-      };
+
+    if (resultOfPrimaryCalls.failure) {
+      yield put(initEditorError());
+      return;
     }
-  } catch (error) {
-    yield put({
-      type: ReduxActionTypes.FETCH_PAGE_DSL_ERROR,
-      payload: {
-        pageId: pageId,
-        error,
-        show: false,
-      },
-    });
-  }
-}
 
-export function* populatePageDSLsSaga() {
-  try {
-    yield put({
-      type: ReduxActionTypes.POPULATE_PAGEDSLS_INIT,
+    yield all([put(fetchPlugins()), put(fetchDatasources())]);
+
+    const resultOfSecondaryCalls = yield race({
+      success: all([
+        take(ReduxActionTypes.FETCH_PLUGINS_SUCCESS),
+        take(ReduxActionTypes.FETCH_DATASOURCES_SUCCESS),
+      ]),
+      failure: take([
+        ReduxActionErrorTypes.FETCH_PLUGINS_ERROR,
+        ReduxActionErrorTypes.FETCH_DATASOURCES_ERROR,
+      ]),
     });
-    const pageIds: string[] = yield select((state: AppState) =>
-      state.entities.pageList.pages.map((page: Page) => page.pageId),
-    );
-    const pageDSLs = yield all(
-      pageIds.map((pageId: string) => {
-        return call(fetchPageDSLSaga, pageId);
-      }),
-    );
-    yield put({
-      type: ReduxActionTypes.FETCH_PAGE_DSLS_SUCCESS,
-      payload: pageDSLs,
+
+    if (resultOfSecondaryCalls.failure) {
+      yield put(initEditorError());
+      return;
+    }
+
+    yield put(updateAppStore(getAppStore(applicationId)));
+
+    const currentApplication = yield select(getCurrentApplication);
+
+    const appName = currentApplication ? currentApplication.name : "";
+    const appId = currentApplication ? currentApplication.id : "";
+
+    AnalyticsUtil.logEvent("EDITOR_OPEN", {
+      appId: appId,
+      appName: appName,
     });
-  } catch (error) {
+
     yield put({
-      type: ReduxActionErrorTypes.POPULATE_PAGEDSLS_ERROR,
-      payload: {
-        error,
-      },
+      type: ReduxActionTypes.INITIALIZE_EDITOR_SUCCESS,
     });
+  } catch (e) {
+    yield put(initEditorError());
+    return;
   }
+
+  yield call(populatePageDSLsSaga);
 }
 
 export function* initializeAppViewerSaga(
@@ -156,11 +123,23 @@ export function* initializeAppViewerSaga(
     put(fetchApplication(applicationId, APP_MODE.PUBLISHED)),
   ]);
 
-  yield all([
-    take(ReduxActionTypes.FETCH_ACTIONS_VIEW_MODE_SUCCESS),
-    take(ReduxActionTypes.FETCH_PAGE_LIST_SUCCESS),
-    take(ReduxActionTypes.FETCH_APPLICATION_SUCCESS),
-  ]);
+  const resultOfPrimaryCalls = yield race({
+    success: all([
+      take(ReduxActionTypes.FETCH_ACTIONS_VIEW_MODE_SUCCESS),
+      take(ReduxActionTypes.FETCH_PAGE_LIST_SUCCESS),
+      take(ReduxActionTypes.FETCH_APPLICATION_SUCCESS),
+    ]),
+    failure: take([
+      ReduxActionErrorTypes.FETCH_ACTIONS_VIEW_MODE_ERROR,
+      ReduxActionErrorTypes.FETCH_PAGE_LIST_ERROR,
+      ReduxActionErrorTypes.FETCH_APPLICATION_ERROR,
+    ]),
+  });
+
+  if (resultOfPrimaryCalls.failure) {
+    yield put(initViewerError());
+    return;
+  }
 
   yield put(updateAppStore(getAppStore(applicationId)));
   const defaultPageId = yield select(getDefaultPageId);
@@ -168,7 +147,15 @@ export function* initializeAppViewerSaga(
 
   if (toLoadPageId) {
     yield put(fetchPublishedPage(toLoadPageId, true));
-    yield take(ReduxActionTypes.FETCH_PUBLISHED_PAGE_SUCCESS);
+
+    const resultOfFetchPage = yield race({
+      success: take(ReduxActionTypes.FETCH_PUBLISHED_PAGE_SUCCESS),
+      failure: take(ReduxActionErrorTypes.FETCH_PUBLISHED_PAGE_ERROR),
+    });
+    if (resultOfFetchPage.failure) {
+      yield put(initViewerError());
+      return;
+    }
 
     yield put(setAppMode(APP_MODE.PUBLISHED));
     yield put(updateAppStore(getAppStore(applicationId)));

app/client/src/sagas/PageSagas.tsx

@@ -1,6 +1,7 @@
 import CanvasWidgetsNormalizer from "normalizers/CanvasWidgetsNormalizer";
 import { AppState } from "reducers";
 import {
+  Page,
   PageListPayload,
   ReduxAction,
   ReduxActionErrorTypes,
@@ -43,7 +44,6 @@ import {
   select,
   takeLatest,
   takeLeading,
-  take,
 } from "redux-saga/effects";
 import history from "utils/history";
 import { BUILDER_PAGE_URL } from "constants/routes";
@@ -117,6 +117,16 @@ export function* fetchPageListSaga(
       PerformanceTracker.stopAsyncTracking(
         PerformanceTransactionName.FETCH_PAGE_LIST_API,
       );
+    } else {
+      PerformanceTracker.stopAsyncTracking(
+        PerformanceTransactionName.FETCH_PAGE_LIST_API,
+      );
+      yield put({
+        type: ReduxActionErrorTypes.FETCH_PAGE_LIST_ERROR,
+        payload: {
+          error: response.responseMeta.error,
+        },
+      });
     }
   } catch (error) {
     PerformanceTracker.stopAsyncTracking(
@@ -608,6 +618,57 @@ export function* setDataUrl() {
   yield put(setUrlData(urlData));
 }
 
+function* fetchPageDSLSaga(pageId: string) {
+  try {
+    const fetchPageResponse: FetchPageResponse = yield call(PageApi.fetchPage, {
+      id: pageId,
+    });
+    const isValidResponse = yield validateResponse(fetchPageResponse);
+    if (isValidResponse) {
+      return {
+        pageId: pageId,
+        dsl: extractCurrentDSL(fetchPageResponse),
+      };
+    }
+  } catch (error) {
+    yield put({
+      type: ReduxActionTypes.FETCH_PAGE_DSL_ERROR,
+      payload: {
+        pageId: pageId,
+        error,
+        show: false,
+      },
+    });
+  }
+}
+
+export function* populatePageDSLsSaga() {
+  try {
+    yield put({
+      type: ReduxActionTypes.POPULATE_PAGEDSLS_INIT,
+    });
+    const pageIds: string[] = yield select((state: AppState) =>
+      state.entities.pageList.pages.map((page: Page) => page.pageId),
+    );
+    const pageDSLs = yield all(
+      pageIds.map((pageId: string) => {
+        return call(fetchPageDSLSaga, pageId);
+      }),
+    );
+    yield put({
+      type: ReduxActionTypes.FETCH_PAGE_DSLS_SUCCESS,
+      payload: pageDSLs,
+    });
+  } catch (error) {
+    yield put({
+      type: ReduxActionErrorTypes.POPULATE_PAGEDSLS_ERROR,
+      payload: {
+        error,
+      },
+    });
+  }
+}
+
 export default function* pageSagas() {
   yield all([
     takeLatest(ReduxActionTypes.FETCH_PAGE_INIT, fetchPageSaga),

app/client/src/selectors/appViewSelectors.tsx

@@ -32,6 +32,11 @@ export const getIsInitialized = createSelector(
   (view: AppViewReduxState) => view.initialized,
 );
 
+export const getIsInitializeError = createSelector(
+  getAppViewState,
+  (view: AppViewReduxState) => view.initializeError,
+);
+
 export const getCurrentDSLPageId = createSelector(
   getPageListState,
   (pageList: PageListReduxState) => pageList.currentPageId,

app/client/src/selectors/editorSelectors.tsx

@@ -20,14 +20,12 @@ import { getDataTree } from "selectors/dataTreeSelectors";
 import _ from "lodash";
 import { ContainerWidgetProps } from "widgets/ContainerWidget";
 import { DataTreeWidget, ENTITY_TYPE } from "entities/DataTree/dataTreeFactory";
-import { getActions, getWidgetsMeta } from "sagas/selectors";
+import { getActions } from "sagas/selectors";
 
-import * as log from "loglevel";
 import PerformanceTracker, {
   PerformanceTransactionName,
 } from "utils/PerformanceTracker";
 import { getCanvasWidgets } from "./entitiesSelector";
-import { MetaState } from "../reducers/entityReducers/metaReducer";
 import { WidgetTypes } from "../constants/WidgetConstants";
 
 const getWidgetConfigs = (state: AppState) => state.entities.widgetConfig;
@@ -45,6 +43,9 @@ const getWidgets = (state: AppState): CanvasWidgetsReduxState =>
 export const getIsEditorInitialized = (state: AppState) =>
   state.ui.editor.initialized;
 
+export const getIsEditorInitializeError = (state: AppState): boolean =>
+  state.ui.editor.initializationError;
+
 export const getIsEditorLoading = (state: AppState) =>
   state.ui.editor.loadingStates.loading;