Unknown web app http://FUNDAMENTAL_DONOTDELETE in ULS

Question

While accessing a site I see this Unexpected ULS entry.

LoadFromDBOrCache: Reverting to not using the cache for cacheKey: cc7d967f-7cff-474e-ab08-31b59370b9b0. Exception: System.IO.FileNotFoundException: The Web Application at http://FUNDAMENTAL_DONOTDELETE_cc7d967f-7cff-474e-ab08-31b59370b9b0 could not be found. Verify that you have typed the URL correctly. If the URL should be serving existing content, the system administrator may need to add a new request URL mapping to the intended application.

The content database comes from a SP 2013 farm that we are in the process of upgrading to SP 2019, via content database upgrade in SP 2016.

Does anyone know what this is all about?

Can it be related to that our 2013 environment is running in multi-tenancy mode?

Answer 1

Yeah this would be due to an MT configuration. You should be able to safely ignore it.