[.NET 5.0 RC1] Script error in Firefox when loading blazor.webassembly.js

[SommerEngineering]

Describe the bug

I have created a new Blazor WASM project with .NET 5.0 RC1. In Microsoft Edge 85.0.564.51 everything works fine. When I load the app in Firefox 68.12.0esr, there is a script error in the blazor.webassembly.js file:

SyntaxError: invalid regexp group blazor.webassembly.js:1:16.

To Reproduce

• Run the following commands:

dotnet new blazorwasm
dotnet publish --configuration Release

• Open the index.html in Firefox 68.12.0esr
• Open the console to see the error

Exceptions (if any)

The wasm app runs.

Further technical details

• Firefox 68.12.0esr

.NET SDK (reflecting any global.json):
 Version:   5.0.100-rc.1.20452.10
 Commit:    473d1b592e

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.17763
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\5.0.100-rc.1.20452.10\

Host (useful for support):
  Version: 5.0.0-rc.1.20451.14
  Commit:  38017c3935

.NET SDKs installed:
  3.1.202 [C:\Program Files\dotnet\sdk]
  3.1.402 [C:\Program Files\dotnet\sdk]
  5.0.100-rc.1.20452.10 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0-rc.1.20451.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0-rc.1.20451.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.0-rc.1.20452.2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

[BruceHunter]

It seems that Firefox is off on their own compared to Chrome/Edge....

Lookbehind regex syntax (which this module uses) is not supported in Firefox.

[mkArtakMSFT]

Thanks for contacting us.
We've validated this with Firefox v. 80 and we can't repro this. Please update your browser to the latest version and that should resolve your issue.