HI! I upgraded to V12 and Microsoft.ICU.ICU4C.Runtime 72.1.0.1, builds with no error. But when run the following issue occurs any ideas:

Do not update that specific library yet. https://github.com/umbraco/Umbraco-CMS/issues/14661

Thanks a lot, I have reverted it back to previous version and all good now. It would be helpful if a warning message is somehow linked to version 72, it just shows as a new version on NuGet.

Just upgraded from 11.4 to 12.1.1 - got simular issues + a couple of more I had to fix: - Downgrade ICU to 68.2.0.9 - If you use Our.Umbraco.DocTypeGridEditor v.10.0.1 - remove it - the views is not compatible - I had to clean the nuget cache due to some old stuff interfering - do this in a terminal - standing in the project folder: - dotnet nuget locals all --clear - dotnet restore - dotnet build - dotnet run (will give you better errors, if any, than starting from VS2022) Then the upgrade was ok..