diff --git a/src/App.tsx b/src/App.tsx
index 9615e22cb..01668300e 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -3,7 +3,9 @@ import React, { withGlobal } from './lib/teact/teactn';
 
 import { GlobalActions, GlobalState } from './global/types';
 
-import { GRAMJS_SESSION_ID_KEY, INACTIVE_MARKER, PAGE_TITLE } from './config';
+import {
+  GRAMJS_SESSION_ID_KEY, INACTIVE_MARKER, LEGACY_SESSION_KEY, PAGE_TITLE,
+} from './config';
 import { pick } from './util/iteratees';
 import { updateSizes } from './util/windowSize';
 import { addActiveTabChangeListener } from './util/activeTabMonitor';
@@ -53,7 +55,10 @@ const App: FC<StateProps & DispatchProps> = ({ authState, disconnect }) => {
     }
   }
 
-  return localStorage.getItem(GRAMJS_SESSION_ID_KEY) ? renderMain() : <Auth />;
+  const hasSession = localStorage.getItem(GRAMJS_SESSION_ID_KEY);
+  const hasLegacySession = localStorage.getItem(LEGACY_SESSION_KEY);
+
+  return (hasSession || hasLegacySession) ? renderMain() : <Auth />;
 };
 
 function renderMain() {
diff --git a/src/api/gramjs/methods/client.ts b/src/api/gramjs/methods/client.ts
index 901b01723..b426c5b3b 100644
--- a/src/api/gramjs/methods/client.ts
+++ b/src/api/gramjs/methods/client.ts
@@ -27,7 +27,7 @@ let onUpdate: OnApiUpdate;
 let client: TelegramClient;
 let isConnected = false;
 
-export async function init(sessionId: string, _onUpdate: OnApiUpdate) {
+export async function init(sessionInfo: string, _onUpdate: OnApiUpdate) {
   onUpdate = _onUpdate;
 
   if (DEBUG) {
@@ -36,8 +36,8 @@ export async function init(sessionId: string, _onUpdate: OnApiUpdate) {
   }
 
   const session = IS_TEST
-    ? new sessions.LocalStorageSession(sessionId)
-    : new sessions.IdbSession(sessionId);
+    ? new sessions.LocalStorageSession(sessionInfo)
+    : new sessions.IdbSession(sessionInfo);
 
   client = new TelegramClient(
     session,
diff --git a/src/api/gramjs/provider.ts b/src/api/gramjs/provider.ts
index 42d50e7b5..e40ee106d 100644
--- a/src/api/gramjs/provider.ts
+++ b/src/api/gramjs/provider.ts
@@ -16,7 +16,7 @@ import * as methods from './methods';
 
 let onUpdate: OnApiUpdate;
 
-export async function initApi(_onUpdate: OnApiUpdate, sessionId = '') {
+export async function initApi(_onUpdate: OnApiUpdate, sessionInfo = '') {
   onUpdate = _onUpdate;
 
   initUpdater(handleUpdate);
@@ -28,7 +28,7 @@ export async function initApi(_onUpdate: OnApiUpdate, sessionId = '') {
   initManagement(handleUpdate);
   initTwoFaSettings(handleUpdate);
 
-  await initClient(sessionId, handleUpdate);
+  await initClient(sessionInfo, handleUpdate);
 }
 
 export function callApi<T extends keyof Methods>(fnName: T, ...args: MethodArgs<T>): MethodResponse<T> {
diff --git a/src/api/gramjs/worker/provider.ts b/src/api/gramjs/worker/provider.ts
index 01ca0d518..40060e42f 100644
--- a/src/api/gramjs/worker/provider.ts
+++ b/src/api/gramjs/worker/provider.ts
@@ -20,7 +20,7 @@ const requestStatesByCallback = new Map<AnyToVoidFunction, RequestStates>();
 
 // TODO Re-use `util/WorkerConnector.ts`
 
-export function initApi(onUpdate: OnApiUpdate, sessionId = '') {
+export function initApi(onUpdate: OnApiUpdate, sessionInfo = '') {
   if (!worker) {
     if (DEBUG) {
       // eslint-disable-next-line no-console
@@ -33,7 +33,7 @@ export function initApi(onUpdate: OnApiUpdate, sessionId = '') {
 
   return makeRequest({
     type: 'initApi',
-    args: [sessionId],
+    args: [sessionInfo],
   });
 }
 
diff --git a/src/config.ts b/src/config.ts
index ad1fd39fc..b83426110 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -15,6 +15,7 @@ export const DEBUG_ALERT_MSG = 'Shoot!\nSomething went wrong, please see the err
 export const DEBUG_GRAMJS = false;
 
 export const GRAMJS_SESSION_ID_KEY = 'GramJs:sessionId';
+export const LEGACY_SESSION_KEY = 'dc';
 
 export const GLOBAL_STATE_CACHE_DISABLED = false;
 export const GLOBAL_STATE_CACHE_KEY = 'tt-global-state';
diff --git a/src/lib/gramjs/sessions/StorageSession.js b/src/lib/gramjs/sessions/StorageSession.js
index 4956cfd4b..bb7db3355 100644
--- a/src/lib/gramjs/sessions/StorageSession.js
+++ b/src/lib/gramjs/sessions/StorageSession.js
@@ -3,12 +3,19 @@ const AuthKey = require('../crypto/AuthKey');
 const utils = require('../Utils');
 
 const STORAGE_KEY_BASE = 'GramJs-session-';
+const SESSION_DATA_PREFIX = 'session:';
 
 class StorageSession extends MemorySession {
-    constructor(sessionId) {
+    constructor(sessionInfo) {
         super();
-        this._storageKey = sessionId;
+
         this._authKeys = {};
+
+        if (sessionInfo && sessionInfo.startsWith(SESSION_DATA_PREFIX)) {
+            void this._initFromSessionData(sessionInfo);
+        } else if (sessionInfo) {
+            this._storageKey = sessionInfo;
+        }
     }
 
     get authKey() {
@@ -87,6 +94,19 @@ class StorageSession extends MemorySession {
         void this._updateStorage();
     }
 
+    async _initFromSessionData(sessionData) {
+        const [, mainDcIdStr, mainDcKey] = sessionData.split(':');
+        const mainDcId = Number(mainDcIdStr);
+        const {
+            ipAddress,
+            port,
+        } = utils.getDC(mainDcId);
+        this.setDC(mainDcId, ipAddress, port);
+        const authKey = new AuthKey();
+        await authKey.setKey(Buffer.from(mainDcKey, 'hex'), true);
+        this.setAuthKey(authKey, mainDcId);
+    }
+
     async _updateStorage() {
         if (!this._storageKey) {
             return;
diff --git a/src/modules/actions/api/initial.ts b/src/modules/actions/api/initial.ts
index 294137f7b..0f4c2a415 100644
--- a/src/modules/actions/api/initial.ts
+++ b/src/modules/actions/api/initial.ts
@@ -11,6 +11,7 @@ import {
   MEDIA_CACHE_NAME,
   MEDIA_CACHE_NAME_AVATARS,
   MEDIA_PROGRESSIVE_CACHE_NAME,
+  LEGACY_SESSION_KEY,
 } from '../../../config';
 import { initApi, callApi } from '../../../api/gramjs';
 import { unsubscribe } from '../../../util/notifications';
@@ -18,9 +19,18 @@ import * as cacheApi from '../../../util/cacheApi';
 import { updateAppBadge } from '../../../util/appBadge';
 
 addReducer('initApi', (global: GlobalState, actions) => {
-  const sessionId = localStorage.getItem(GRAMJS_SESSION_ID_KEY) || undefined;
+  let sessionInfo = localStorage.getItem(GRAMJS_SESSION_ID_KEY) || undefined;
 
-  void initApi(actions.apiUpdate, sessionId);
+  if (!sessionInfo) {
+    const legacySessionMainDc = localStorage.getItem(LEGACY_SESSION_KEY);
+    const legacySessionMainDcKey = localStorage.getItem(`dc${legacySessionMainDc}_auth_key`);
+
+    if (legacySessionMainDc && legacySessionMainDcKey) {
+      sessionInfo = `session:${legacySessionMainDc}:${legacySessionMainDcKey}`;
+    }
+  }
+
+  void initApi(actions.apiUpdate, sessionInfo);
 });
 
 addReducer('setAuthPhoneNumber', (global, actions, payload) => {