Upgrading in Visual Studio from 13.7.2 to 13.8.0 gives no error, but when I try to build the solution I get this error:
InvalidOperationException: Sequence contains more than one element
at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
at Microsoft.AspNetCore.StaticWebAssets.Tasks.GenerateStaticWebAssetsDevelopmentManifest.<ComputeManifestAssets>d__19.MoveNext()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at Microsoft.AspNetCore.StaticWebAssets.Tasks.GenerateStaticWebAssetsDevelopmentManifest.ComputeDevelopmentManifest(IEnumerable`1 assets, IEnumerable`1 discoveryPatterns)
at Microsoft.AspNetCore.StaticWebAssets.Tasks.GenerateStaticWebAssetsDevelopmentManifest.Execute()
I had the same problem. It turned out to be down to Umbraco Engage, which was creating an extra folder in wwwroot/App_Plugins. When I excluded this folder from the solution, the project built fine. I think the latest version of Engage no longer creates this folder.
My guess is that an older version of Engage was not yet a Razor Class Library. Older packages would have a ‘task’ so to speak that copies over App_Plugins files from the NuGet folder to the actual project. But when the package is converted to a Razor Class Library, the files are no longer physically required in the App_Plugins folder (or at least not during development, they get copied over on publish). If you have older files in App_Plusing that are no longer required, they might conflict.
I reinstalled the site and then I used the default publish folder (bin/release/net8.0/publish), and then upgrading works. I guess having the publish folder the same as the project root folder, which I had at first, it’s not recommended. Thank you for giving me tips.