[Problem/Bug]: Partly broken PDF toolbar in runtime 148.0.3967.54 leading to crashing control

[mbidinger-coder]

What happened?

We're using the WebView2 control in different Winforms applications to display and print locally stored PDF files.
Since today (2026/05/12) we started receiving reports from our users that printing was no longer possible.
While investigating the issue, we observed that on all affected systems, the installed evergreen version of WebView had updated to runtime 148.0.3967.54, but no reports at all from systems which still were on runtime 147.0.3912.98.

The issue is present while viewing a PDF file with the integrated PDF viewer.
On version 147.0.3912.98 and before, the PDF toolbar can be used normally.
On version 148.0.3967.54, some of the toolbar functions (e.g. clicking the gear icon or the 3-dot icon) cause the whole WebView2 control to crash, leaving the WebView2 control area either black or gray.

No error caught by the application that we noticed.
Also no crash report in "EBWebView\Crashpad\reports" of the WebView2 user data.

We confirmed this behavior to be present in the evergreen and standalone runtimes while investigating, both in .NET Framework 4.8 and .NET 10 so far.

Importance

Important. My app's user experience is significantly compromised.

Runtime Channel

Stable release (WebView2 Runtime)

Runtime Version

148.0.3967.54

SDK Version

1.0.3967.48

Framework

Winforms

Operating System

Windows 11

OS Version

26200.8246

Repro steps

1. Create a Winforms C# project in .NET 10.
2. Add NuGet packages Microsoft.Web.WebView2 and WebView2.Runtime.X86.
3. Add a WebView2 control to the form and start up the CoreWebView2 with the linked standalone runtime.
4. Load a local PDF file into the WebView2 control through the Source property.
5. Click on the gear or 3-dot icon in the PDF toolbar.

In the attached solution are 2 projects to reproduce the issue (for runtime 147 and 148).
Simply drag a PDF file into the drag&drop area of the forms and click on the mentioned toolbar icons.

WebView2Pdf.zip

Runtime 147.0.3912.98, after clicking the gear icon (marked for emphasis):

Runtime 148.0.3967.54, before clicking the gear icon:

Runtime 148.0.3967.54, after clicking the gear icon:

Repros in Edge Browser

No, issue does not reproduce in the corresponding Edge version

Regression

Regression in newer Runtime

Last working version (if regression)

147.0.3912.98

[github-actions]

Hi, @mbidinger-coder!

It seems that your issue contains the word "crash". If you have not already, could you attach a crash dump as a comment?

WV2 crash dumps are located in a subfolder of the app's user data folder (UDF): <UDF>\EBWebView\Crashpad\reports\. By default, the user data folder is created in the app's folder with a name like <App Exe Name>.exe.WebView2. Refer to Crash Diagnostics for more information.

Thank you for your cooperation!