Runtime: ValueTuple compatibility issues in .NET Framework 4.7.1

[mkosieradzki]

Cross posting for better visibility:
Microsoft/dotnet-framework-early-access#9

Fall creators update is going live in two days. Heads up! It will generate nasty compat issues for applications using Task<ValueTuple>. Not sure if this is a known issue or by design, but I have lost entire day today trying to track it down.

[karelz]

@ericstj @weshaggard @jcouv is this a known problem?

[weshaggard]

@AlexGhiondea is this problem known? If not we probably should investigate to understand it.

[AlexGhiondea]

This was not know. But what is happening is that the System.ValueTuple that gets loaded is the one carried with the app -- there is a binding redirect in the .config file that forces that. Removing the binding redirect allows the app to work.

[mkosieradzki]

Yup. Commenting out this single binding redirect:

   <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.ValueTuple" publicKeyToken="cc7b13ffcd2ddd51" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.0.2.0" newVersion="4.0.2.0" />
      </dependentAssembly>
    </assemblyBinding>

Makes the application run without any issues.

[weshaggard]

@AlexGhiondea so binding redirects overwrite the unification table? If that is the case we might be hitting other similar issues with other things we moved inbox.

[mkosieradzki]

If I understand correctly .NET Framework 4.7.1 today starts getting rolled out to customers through the Windows Update (inside the Fall Creators Update)? It's Oct 17th... I am a bit afraid it might break some apps... including ours... before you even have a chance to fix this issue.

[AlexGhiondea]

@weshaggard yes, the binding redirects override the unification table.

[marchy]

After the Windows Update our code now fails at runtime with "Method not found: 'System.ValueTuple`2" wherever tuples get invoked.

Cannot seem to find a way around this. Our codebase targets 'net462' (as to run on Azure) but local machines are now on 4.7.1. What to do?

[mkosieradzki]

@marchy The only reasonable workaround I know is to retarget to net47.

[AlexGhiondea]

Hey @marchy this is a known issue in 4.7.1. More information about it is here

Currently the workaround is to either manually remove the binding redirects to System.ValueTuple of, as @mkosieradzki mentioned, re-target the application to 4.7 or 4.7.1.

We are working on a fix for this.

[marchy]

Thanks for the very prompt reply @AlexGhiondea @mkosieradzki.

Re-targeting to 4.7 solved it :)
(while re-targeting to 4.7.1 is not feasible since apparently Azure doesn't expect support for it until December)

[joperezr]

Closing this issue as this problem is now being tracked in a different repo: https://github.com/dotnet/standard/issues/567

Just as a small FYI, this problem has been addressed in the next version of .NET Framework and a fix for it will be serviced to 4.7.1 machines.