Could not load file or assembly 'System.ValueTuple'

ok this feels completely wrong but I cut

  <dependentAssembly>
    <assemblyIdentity name="System.ValueTuple" publicKeyToken="cc7b13ffcd2ddd51" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-4.0.3.0" newVersion="4.0.3.0" />
  </dependentAssembly>

This out of my web.config for the main application.

I was really just seeing what happened to see if there was an underlying dependency or something, not expecting it to run. It just carried on working, all the new functions I have added in the last few days still work.

I just had this issue myself. Not on Localhost while developing, but only on production server. In the end it turned out to be some sort of conflict between .Net Framework 4.6.1 and me having System.ValueTuple installed from Nuget in version 4.5.0.

The solution turned out to be, to downgrade the System.ValueTuple Nuget package to 4.3.0. Then it worked, like nothing had ever been an issue.

I suspect that this only happened on production server, cause of a different version of .net framework installed.