Invalid configuration: endpoints.ps1

What to make of this repeated notification message? Description reads “Object reference not set to an instance of an object.”
The API endpoint scripts do not have errors.
Where can I find more about this error? It does not appear in the Universal log files. It seemed to start after API was switched to run under an external environment.
I’m running last 3.9.x version.

Prior to “Object not set…” the Description contains gRPC exceptions related to “Stream Removed”