diff --git a/webapp/packages/core-bootstrap/src/manifest.ts b/webapp/packages/core-bootstrap/src/manifest.ts
index 56933cf17e..0d540b85e8 100644
--- a/webapp/packages/core-bootstrap/src/manifest.ts
+++ b/webapp/packages/core-bootstrap/src/manifest.ts
@@ -78,6 +78,7 @@ import { LocalizationService } from '@cloudbeaver/core-localization';
 import { PluginManagerService } from '@cloudbeaver/core-plugin';
 import { ProductManagerService, ProductSettingsService } from '@cloudbeaver/core-product';
 import {
+  NetworkStateService,
   SessionService,
   ServerService,
   PermissionsService,
@@ -104,6 +105,7 @@ export const coreManifest: PluginManifest = {
 
   providers: [
     RouterService, // important, should be first because the router starts in load phase first after all plugins register phase
+    NetworkStateService,
     AdministrationLocaleService,
     AdministrationTopAppBarService,
     AdministrationScreenService,
diff --git a/webapp/packages/core-root/src/NetworkError.ts b/webapp/packages/core-root/src/NetworkError.ts
new file mode 100644
index 0000000000..f9ba8896be
--- /dev/null
+++ b/webapp/packages/core-root/src/NetworkError.ts
@@ -0,0 +1,15 @@
+
+/*
+ * CloudBeaver - Cloud Database Manager
+ * Copyright (C) 2020-2021 DBeaver Corp and others
+ *
+ * Licensed under the Apache License, Version 2.0.
+ * you may not use this file except in compliance with the License.
+ */
+
+export class NetworkError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = 'NetworkError';
+  }
+}
diff --git a/webapp/packages/core-root/src/NetworkStateService.ts b/webapp/packages/core-root/src/NetworkStateService.ts
new file mode 100644
index 0000000000..337c85986f
--- /dev/null
+++ b/webapp/packages/core-root/src/NetworkStateService.ts
@@ -0,0 +1,78 @@
+/*
+ * CloudBeaver - Cloud Database Manager
+ * Copyright (C) 2020-2021 DBeaver Corp and others
+ *
+ * Licensed under the Apache License, Version 2.0.
+ * you may not use this file except in compliance with the License.
+ */
+
+import { makeObservable, observable } from 'mobx';
+
+import { Bootstrap, injectable } from '@cloudbeaver/core-di';
+import { Executor, IExecutor } from '@cloudbeaver/core-executor';
+import { GraphQLService } from '@cloudbeaver/core-sdk';
+
+import { NetworkError } from './NetworkError';
+
+@injectable()
+export class NetworkStateService extends Bootstrap {
+  get state(): boolean {
+    return this.networkState;
+  }
+
+  readonly networkStateExecutor: IExecutor<boolean>;
+  private networkState: boolean;
+
+  constructor(
+    private graphQLService: GraphQLService
+  ) {
+    super();
+    makeObservable<NetworkStateService, 'networkState'>(this, {
+      networkState: observable,
+    });
+
+    this.networkState = true;
+    this.networkStateExecutor = new Executor();
+  }
+
+  register(): void {
+    this.networkState = window.navigator.onLine;
+
+    window.addEventListener('online', () => this.setState(true));
+    window.addEventListener('offline', () => this.setState(false));
+
+    this.graphQLService.registerInterceptor(this.sessionExpiredInterceptor.bind(this));
+  }
+
+  load(): void {}
+
+  private setState(state: boolean) {
+    if (this.networkState === state) {
+      return;
+    }
+
+    if (state) {
+      if (this.graphQLService.client.blockReason instanceof NetworkError) {
+        this.graphQLService.enableRequests();
+      }
+    } else {
+      this.graphQLService.blockRequests(new NetworkError('Network connection was lost'));
+    }
+    this.networkState = state;
+    this.networkStateExecutor.execute(this.networkState);
+  }
+
+  private async sessionExpiredInterceptor(request: Promise<any>): Promise<any> {
+    try {
+      return await request;
+    } catch (exception) {
+      if (
+        exception instanceof TypeError
+        && exception.message === 'Failed to fetch'
+      ) {
+        throw new NetworkError('Error while processing request');
+      }
+      throw exception;
+    }
+  }
+}
diff --git a/webapp/packages/core-root/src/index.ts b/webapp/packages/core-root/src/index.ts
index 54c1c80c4f..84e2b35431 100644
--- a/webapp/packages/core-root/src/index.ts
+++ b/webapp/packages/core-root/src/index.ts
@@ -1,4 +1,6 @@
 export * from './ConnectionNavigatorViewSettings';
+export * from './NetworkError';
+export * from './NetworkStateService';
 export * from './PermissionsResource';
 export * from './PermissionsService';
 export * from './ServerConfigResource';
diff --git a/webapp/packages/core-sdk/src/CustomGraphQLClient.ts b/webapp/packages/core-sdk/src/CustomGraphQLClient.ts
index 65faa8ca28..5390073ebf 100644
--- a/webapp/packages/core-sdk/src/CustomGraphQLClient.ts
+++ b/webapp/packages/core-sdk/src/CustomGraphQLClient.ts
@@ -13,9 +13,13 @@ import { GQLError } from './GQLError';
 import type { IResponseInterceptor } from './IResponseInterceptor';
 
 export class CustomGraphQLClient extends GraphQLClient {
+  get blockReason(): Error | string | null {
+    return this.requestsBlockedReason;
+  }
+
   private interceptors: IResponseInterceptor[] = [];
   private isRequestsBlocked = false;
-  private requestsBlockedReason?: Error | string;
+  private requestsBlockedReason: Error | string | null = null;
 
   registerInterceptor(interceptor: IResponseInterceptor): void {
     this.interceptors.push(interceptor);
@@ -28,6 +32,11 @@ export class CustomGraphQLClient extends GraphQLClient {
     );
   }
 
+  enableRequests(): void {
+    this.isRequestsBlocked = false;
+    this.requestsBlockedReason = null;
+  }
+
   blockRequests(reason: Error | string): void {
     this.isRequestsBlocked = true;
     this.requestsBlockedReason = reason;
@@ -38,7 +47,7 @@ export class CustomGraphQLClient extends GraphQLClient {
       if (this.requestsBlockedReason instanceof Error) {
         throw this.requestsBlockedReason;
       } else {
-        throw new Error(this.requestsBlockedReason);
+        throw new Error(this.requestsBlockedReason ?? undefined);
       }
     }
   }
diff --git a/webapp/packages/core-sdk/src/GraphQLService.ts b/webapp/packages/core-sdk/src/GraphQLService.ts
index 1ae8df23ff..60f5413c6e 100644
--- a/webapp/packages/core-sdk/src/GraphQLService.ts
+++ b/webapp/packages/core-sdk/src/GraphQLService.ts
@@ -29,6 +29,10 @@ export class GraphQLService {
     this.client.registerInterceptor(interceptor);
   }
 
+  enableRequests(): void {
+    this.client.enableRequests();
+  }
+
   blockRequests(reason: Error | string): void {
     this.client.blockRequests(reason);
   }