I was very anticipating to upgrade my solution to recently released XP 9.1 with SXA 1.8 and all its great features, however, I got a dependency on Sitecore Commerce, which hasn't (yet) updated to 9.1. Got nothing to do with that, but just wait for a month or so until XC 9.1 is out...
But wait, why not just update at least SXA to version 1.8 meanwhile? SXA 1.8 comes for both versions for 9.1 and 9.0 which means - in two runtimes .NET 4.7.1 and .NET 4.6.2 correspondingly. Done, upgraded. SXA 1.8 works well on top of clean Sitecore 9.0 update 2 instance for me.
But when it came to updating NuGet packages in my solution, I was unable to do so because NuGet packages for my version for some reason demand .NET 4.7.1:
And that is my error:
Package Sitecore.XA.Feature.CreativeExchange 3.8.0 is not compatible with net462 (.NETFramework,Version=v4.6.2) / win-x86. Package Sitecore.XA.Feature.CreativeExchange 3.8.0 supports: net471 (.NETFramework,Version=v4.7.1)
Version 3.8.0 is the correct version of SXA 1.8 for 9.0 and it should support .NET 4.6.2, not 4.7.2. Version of SXA 1.8 for 9.1 has number 4.8.0 and that one indeed supports 4.7.1 runtime.
Since I cannot do anything about NuGet feeds, I turned back to the old lib\LocalRepository folder in my solution, simply copying all the required SXA 1.8 libraries from instance webroot (where I have SXA 1.8 working with clean 9.0 update instance) and referencing them instead from affected projects.
That did me a job for the moment. I will either update to the NuGets once it is fixed with the correct version or upgrade the entire solution to 9.1 when XC 9.1 is out, whatever comes earlier.