didn't work. try reverting global.json sdk version

appveyor.yml

@@ -34,22 +34,3 @@ build_script:
 
 
     rem appveyor UpdateBuild -Version %BUILDFILE%
-
-install:
- - ps: Write-Host "Installing .NET Core 3.1 SDK..." -ForegroundColor Cyan
- - ps: Write-Host "Downloading..."
- - ps: $exePath = "$env:TEMP\dotnet-sdk-3.1.404-win-x64.exe"
- - ps: (New-Object Net.WebClient).DownloadFile('https://download.visualstudio.microsoft.com/download/pr/3366b2e6-ed46-48ae-bf7b-f5804f6ee4c9/186f681ff967b509c6c9ad31d3d343da/dotnet-sdk-3.1.404-win-x64.exe', $exePath)
- - ps: Write-Host "Installing..."
- - ps: cmd /c start /wait "$exePath" /quiet /norestart
- - ps: del $exePath
- - ps: Write-Host "Installed" -ForegroundColor Green
- - ps: 
- - ps: Write-Host "Installing .NET 5.0 SDK..." -ForegroundColor Cyan
- - ps: Write-Host "Downloading..."
- - ps: $exePath = "$env:TEMP\dotnet-sdk-5.0.100-win-x64.exe"
- - ps: (New-Object Net.WebClient).DownloadFile('https://download.visualstudio.microsoft.com/download/pr/2892493e-df43-409e-af68-8b14aa75c029/53156c889fc08f01b7ed8d7135badede/dotnet-sdk-5.0.100-win-x64.exe', $exePath)
- - ps: Write-Host "Installing..."
- - ps: cmd /c start /wait "$exePath" /quiet /norestart
- - ps: del $exePath
- - ps: Write-Host "Installed" -ForegroundColor Green

global.json

@@ -1,6 +1,6 @@
 {
 	"sdk": {
-		"version": "5.0.100",
+		"version": "3.1.100",
 		"rollForward": "latestFeature"
 	}
 }