[10.0.2] "A fatal error has occurred loading the metadata for 'System.Private.CoreLib.dll' and debugging needs to be terminated."

[ilonatommy]

Reported in dotnet/aspnetcore#65122 (comment).

I verified on 10.0.102 and it's a real issue.

The targets are in a state from before #120330. Is it possible that this change was not the real offender there?

Reproduction:

• download 10.0.102 in zip from https://dotnet.microsoft.com/en-us/download/dotnet/10.0
• unpack, set the terminal to use its location, create wasm browser app, launch VS

$env:PATH = "c:\Users\user\Downloads\dotnet-sdk-10.0.102-win-x64;$env:PATH"
$env:DOTNET_ROOT = "c:\Users\user\Downloads\dotnet-sdk-10.0.102-win-x64"
dotnet --version
dotnet workload install wasm-experimental
dotnet new wasmbrowser -o WasmBrowser
cd "C:\Program Files\Microsoft Visual Studio\18\Insiders\Common7\IDE"
.\devenv.com

• run with debugging (F5)
• popup with Failed to run the project with error "A fatal error has occurred loading the metadata for 'System.Private.CoreLib.dll'" appears

Dlls, including System.Private.Corelib are in the bin/Debug/net10.0 dir.

Binlog:
vs-build.zip

[dotnet-policy-service]

Tagging subscribers to 'arch-wasm': @lewing, @pavelsavara
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[dotnet-policy-service]

Tagging subscribers to this area: @steveisok, @thaystg, @dotnet/dotnet-diag
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[thaystg]

I can't reproduce it, for me it's working fine.
'Managed Wasm Debugger' (Mono: Default Domain): Loaded 'C:\diag\mono\123659\WasmBrowser\bin\Debug\net10.0\System.Private.CoreLib.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.

[ilonatommy]

 Loaded 'c:\Users\user\Downloads\dotnet-sdk-10.0.102-win-x64\shared\Microsoft.NETCore.App\10.0.2\System.Private.CoreLib.dll'. Symbol loading disabled by Include/Exclude setting.
...
 Exception thrown: 'System.Threading.Tasks.TaskCanceledException' in System.Private.CoreLib.dll
...
 'Managed Wasm Debugger' (Mono: Default Domain): Loaded 'System.Collections.dll'. Symbol loading disabled by Include/Exclude setting.
'Managed Wasm Debugger' (Mono: Default Domain): Failed to load metadata for 'System.Private.CoreLib.dll', possibly because the process is corrupt.

VS is trying to load the System.Private.CoreLib.dl from the sdk instead of from mono wasm runtime from some reason, not like in @thaystg's log. Enabling "just my code" makes it only worse:

'dotnet.exe' (CoreCLR: DefaultDomain): Loaded 'c:\Users\user\Downloads\dotnet-sdk-10.0.102-win-x64\shared\Microsoft.NETCore.App\10.0.2\System.Private.CoreLib.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'dotnet.exe' (CoreCLR: clrhost): Loaded 'c:\Users\user\Downloads\dotnet-sdk-10.0.102-win-x64\sdk\10.0.102\dotnet.dll'. Skipped loading symbols.
'dotnet.exe' (CoreCLR: clrhost): Loaded 'c:\program files\microsoft visual studio\18\insiders\common7\ide\extensions\microsoft\managedprojectsystem\HotReload\net10.0\Microsoft.Extensions.DotNetDeltaApplier.dll'. Skipped loading symbols.
'dotnet.exe' (CoreCLR: clrhost): Loaded 'c:\program files\microsoft visual studio\18\insiders\common7\ide\extensions\microsoft\managedprojectsystem\HotReload\net6.0\Microsoft.AspNetCore.Watch.BrowserRefresh.dll'. Skipped loading symbols.
'dotnet.exe' (CoreCLR: clrhost): Loaded 'C:\Program Files\Microsoft Visual Studio\18\Insiders\Common7\IDE\PrivateAssemblies\Runtime\Microsoft.VisualStudio.Debugger.Runtime.NetCoreApp.dll'. Skipped loading symbols.

The thread '.NET Long Running Task' (46296) has exited with code 0 (0x0).
The thread '.NET Long Running Task' (45344) has exited with code 0 (0x0).
The thread 'DrainPacketQueueThread' (44992) has exited with code 0 (0x0).
The thread 'Terminal Logger Node Display Refresher' (19100) has exited with code 0 (0x0).
The thread 'MSBuild LoggingService events queue pump: 43904821' (40316) has exited with code 0 (0x0).

The program '[42012] dotnet.exe' has exited with code 3762504530 (0xe0434352).