@captainsafia , @gfoidl , please have a closer look at the problem @Toudahl is complaining.

Here is the problematic part in Microsoft.Extensions.DependencyInjection.MvcCoreServiceCollectionExtensions

The fact that the value is set by default to the entry-point assembly name, doesn't allow to treat the ApplicationName as assembly name and try loading it !!!

This is breaking change that is not even documented.

Also, even though the manager instance could be provided via DI, the PopulateDefaultParts method is internal !!! and not marked as override - I hardly understand the reason behind letting user to injects their own implementation if he can't provide his own implementation of PopulateDefaultParts method.

Please reopen and provide estimations for the fix.
Thanks

Originally posted by @jvmlet in #53791