We recently needed to rebuild our 10.9.1 Enterprise system from scratch after an failed upgrade from 10.7.0 and are encountering a roadblock when trying to register a custom widget to our Portal. I follow the directions as per the Esri Add Custom Widgets document for Enterprise 10.9.1 but receive the error message "The URL does not reference an AppBuilder Extension."
I have had some concerns from the start given that the menu lacks the Title and Tags options from the example in the directions and all the examples in the various help postings and videos I've found while searching for a solution.
I had no problems registering custom widgets previously with instructions I received from a colleague -
"Un-zip the widget folder, you should be able to copy that entire folder (such as eSearch - with all the items within it) and paste it on the C drive of the Portal server at: C:\inetpub\wwwroot
Then, look at the 'manifest.json' file, and follow the instructions for Add a Custom Widget, starting at the 'Register a custom widget' section."
In that location the widget files should be publicly available and avoiding the issue referenced in the BrianVan_Nostrand post:
"The URL doe not reference an AppBuilder Application" when deploying custom web application
What does "The URL does not reference an AppBuilder Extension" mean? What should be referenced and how?