UseDeveloperExceptionPage plain-text response should set charset

[garryxiao]

Describe the bug

In ASP.NET Core 3.0 and later, the Developer Exception Page displays a plain-text response if the client doesn't request HTML-formatted output. The problem is, when display plain-text response, there is no charset set, just "Content-Type: text/plain" causing garbled when view the text but HTML-formatted output will set with "Content-Type: text/html; charset=utf-8" works.

To Reproduce

Exceptions (if any)

Further technical details

• ASP.NET Core version
• Include the output of dotnet --info
• The IDE (VS / VS Code/ VS4Mac) you're running on, and its version

[rafikiassumani-msft]

@davidfowl and @halter73 is this something we can address as part of the following issue #35857 ?

[davidfowl]

Nope, this is unrelated.

[adityamandaleeka]

https://source.dot.net/#Microsoft.AspNetCore.Diagnostics/DeveloperExceptionPage/DeveloperExceptionPageMiddleware.cs,151

We're using WriteAsync which will use utf-8 here. We should update the content-type here.

[davidfowl]

Are we gonna backport this fix?

[halter73]

We did. #36072