title: Azure CI pipeline for Blazor .NET 5 doesn't work
body: <p>I have an existing Azure CI pipeline for a WebAssembly Blazor application, that works with .NET Core 3.1.</p>
  <p>I upgraded the application to use .NET 5 RC, and the pipeline doesn't work anymore.</p>
  <p>Following suggestions, I removed the NuGet task, and I inserted two new tasks:</p>
  <pre><code>- task: UseDotNet@2
    displayName: 'Use .NET Core sdk 5.0.100-rc.1.20452.10'
    inputs:
      version: '5.0.100-rc.1.20452.10'
      includePreviewVersions: true
  
  - task: DotNetCoreCLI@2
    displayName: 'dotnet restore'
    inputs:
      command: restore
      projects: '**/*.csproj'
  </code></pre>
  <p>that work.</p>
  <p>But the build task fails with:</p>
  <pre><code>...
  ValidateSolutionConfiguration:
    Building solution configuration &quot;release|any cpu&quot;.
    It was not possible to find any installed .NET Core SDKs
    Did you mean to run .NET Core SDK commands? Install a .NET Core SDK from:
        https://aka.ms/dotnet-download
  ##[error]Test1\Server\Server.csproj(0,0): Error : Unable to locate the .NET Core SDK. Check that it is installed and that the version specified in global.json (if any) matches the installed version.
  D:\a\1\s\Test1\Server\Server.csproj : error : Unable to locate the .NET Core SDK. Check that it is installed and that the version specified in global.json (if any) matches the installed version.
  ##[error]Test1\Server\Server.csproj(0,0): Error MSB4236: The SDK 'Microsoft.NET.Sdk.Web' specified could not be found.
  Project &quot;D:\a\1\s\FluidTickets.sln&quot; (1) is building &quot;D:\a\1\s\Test1\Server\Server.csproj&quot; (2) on node 1 (default targets).
  D:\a\1\s\Test1\Server\Server.csproj : error MSB4236: The SDK 'Microsoft.NET.Sdk.Web' specified could not be found.
  Done Building Project &quot;D:\a\1\s\Test1\Server\Server.csproj&quot; (default targets) -- FAILED.
  ...
  </code></pre>
  <p>In another answer here in StackOverflow, I read about adding a new variable:</p>
  <pre><code>MSBuildSDKsPath = C:\agent\_work\_tool\dotnet\sdk\5.0.100-rc.1.20452.10\Sdks
  </code></pre>
  <p>But if I do this, it's the restore task to fail, before the build one. So it looks like the SDK is 'reachable', in some way...<br />
  Any other idea?<br />
  Thanks in advance.</p>