[Problem/Bug]: attachment:// scheme not working anymore

[Hyrius]

What happened?

I have links referencing attachment://file.ext that I handled programmatically, but it just stopped working and now I'm getting the Uri as about:blank#blocked in my events. Did anything change?

Importance

Blocking. My app's basic functions are not working due to this issue.

Runtime Channel

Prerelease (Edge Canary/Dev/Beta)

Runtime Version

133.0.3065.39

SDK Version

No response

Framework

Winforms

Operating System

Windows 11

OS Version

No response

Repro steps

It's a manually loaded HTML page containing links like <a href="attachment://file.jpg">attachment 1</a> and I used to be able to deal with them programmatically in the NavigationStarting event.
Now, e.Uri is about:blank#blocked.

It seems to only occur in links added using JavaScript, a sample project was added in the comments.

Repros in Edge Browser

No response

Regression

Regression in newer Runtime

Last working version (if regression)

132.0.2957.140

[Hyrius]

I tried it in a new project and it worked as expected. I will keep trying to understand what's going on.

[Hyrius]

I did some more testing, and the issue didn’t occur because I was testing on another machine with Runtime 132.0.2957.140.
However, the exact same code doesn’t work (it navigates to about:blank#blocked) in Runtime 133.0.3065.39.
The SDK version appears to be irrelevant.
The issue is probably related to links added via JavaScript… I think?

WebView2CustomSchemeTest.zip

[ParadoxZero]

@Hyrius please share a snippet of how you are using the API.

[Hyrius]

@Hyrius please share a snippet of how you are using the API.

Hey! I attached a sample project in my last comment. Clicking the link in the WebView2 works if the Runtime is 132, but is blocked if it is 133.

[ParadoxZero]

Thanks @Hyrius, somehow my brain skipped over it. Marking the regression as tracked.

[prija-microsoft]

This is due to "|" not a valid character in URL path. which makes the URL invalid. This is in line with what is true with edge/chrome behavior.
Can you try using a valid URL character as per https://www.rfc-editor.org/rfc/rfc3986.

Also I do see you are handling navigationStarting event and cancelling the request. You can also look at implementing custom scheme and listening to WebResourceRequested event for that filter.

[Hyrius]

I'm canceling in this example to prevent navigation to about:blank#blocked, which would make the link disappear.
Regarding the custom scheme, I hadn’t set it up before (in 132), but it still worked. I tried setting it up in version 133 to see if it made a difference, but nothing changed. I'll try again without the "|" character.

It worked perfectly in Runtime version 133 with valid links, and I didn’t need to implement a custom scheme for my use case.
Thanks for the clarification and for helping me understand what I did wrong.

[prija-microsoft]

@Hyrius I tried with runtime 132 as well, and it is failing with "|". Can you please share etw traces if it is working for older runtime.

[Hyrius]

@prija-microsoft Okay, so I did what you asked, but it seems like it failed...

I think the ETL file wasn't created.