Note
Access to this page requires authorization. You can try signing in or changing directories.
Access to this page requires authorization. You can try changing directories.
Release notes for Microsoft Edge WebView2 Prerelease SDK, release date: Feb. 16, 2026.
NuGet package for WebView2 SDK 1.0.3848-prerelease
For full API compatibility, this Prerelease version of the WebView2 SDK requires the WebView2 Runtime that ships with Microsoft Edge version 146.0.3848.0 or later; see Runtime 146.0.3856.49 (Mar. 16, 2026).
Detailed contents:
- Breaking change: Enable WebView2-specific Javascript APIs for service workers
- Breaking change: Local Network Access (LNA) in WebView2
- Experimental APIs (Phase 1: Experimental in Prerelease)
- See also
Breaking change: Enable WebView2-specific Javascript APIs for service workers
The new AreWebViewScriptApisEnabledForServiceWorkers setting provides an explicit and reliable way to control the availability of WebView2‑specific JavaScript APIs (chrome.webview) within service worker scripts.
This setting is disabled by default for WebView2 applications. Apps that don't explicitly enable this setting won't have access to WebView2‑specific JavaScript APIs in service worker scripts. As a result, service worker–based chrome.webview.postMessage communication with the WebView2 host application will not function unless the setting is enabled.
Going forward, WebView2 will rely on the AreWebViewScriptApisEnabledForServiceWorkers setting as the authoritative mechanism for enabling WebView2‑specific JavaScript APIs in service worker scripts. This ensures predictable, secure, and deterministic behavior.
You can proactively validate your WebView2 app's behavior by enabling service worker JavaScript API exposure in your WebView2 app. To do so, configure your app to enable the following setting:
AreWebViewScriptApisEnabledForServiceWorkers = true
By testing your WebView2 app with this setting enabled, you can identify any workflows that depend on WebView2‑specific service worker APIs, such as chrome.webview.postMessage communication between service workers and the host application.
Currently, the chrome and chrome.webview objects are available to service worker scripts when using the ServiceWorkerRegistered event. However, starting with the next release, the AreWebViewScriptApisEnabledForServiceWorkers setting will be the sole mechanism that determines whether these objects are exposed to service worker scripts. Please test this setting before the next release, and report any issues you encounter. For details, see [Breaking Change] Enabling WebView2 specific JavaScript API's for Service Workers.
See also Control whether WebView Script APIs are enabled for service workers, below.
CoreWebView2ProfileClassCoreWebView2ServiceWorkerManagerClass:WebView class in the JavaScript Reference.
chrome.webview.postMessagein the JavaScript Reference.
Breaking change: Local Network Access (LNA) in WebView2
The Chromium browser engine has introduced Local Network Access (LNA). LNA is a security feature that prevents webpages from making requests to private or local network resources, unless the webpage has explicit permission to access the private or local network resources. Examples of such resources are localhost, 192.168.*, or 10.*.
LNA is currently disabled by default for WebView2 apps, but you can enable LNA support via the msWebViewAllowLocalNetworkAccessChecks flag. For WebView2 apps, no action is required at this time. For information about the flag, see Available WebView2 browser flags in WebView2 browser flags.
After the upstream, Chromium code base stabilizes, we plan to add additional enum values in the CoreWebView2PermissionKind enum, to support LNA via the SetPermissionState method. These new enum values will be used by the UWP WebView.PermissionRequested event, to give your WebView2 app explicit control over the Local Network Access (LNA) feature.
CoreWebView2ProfileClass:
You can proactively test the Local Network Access (LNA) feature in your WebView2 app. To test your app with the LNA feature, launch your WebView2 app with the following flag:
--enable-features=LocalNetworkAccessChecks,msWebViewAllowLocalNetworkAccessChecks
By testing your app when launched with this flag, you can then identify any workflows that might be affected by the LNA feature.
After the LNA feature stabilizes, we'll share an updated timeline for enabling the LNA feature. For details, see [Breaking Change] Local Network Access (LNA) in WebView2 - Rollout Plan.
Experimental APIs (Phase 1: Experimental in Prerelease)
The following APIs are in Phase 1: Experimental in Prerelease, and have been added in this Prerelease SDK.
Control whether WebView Script APIs are enabled for service workers
Use the AreWebViewScriptApisEnabledForServiceWorkers property on CoreWebView2Profile to control whether WebView Script APIs are enabled for service workers.
See also Breaking change: Enable WebView2-specific Javascript APIs for service workers, above.
CoreWebView2ProfileClass