How do I replace an old basemap URL for a new URL in a web map

[JayHodny]

Hello.  I am using the Story Map Shortlist solution to show proposed housing developments around town.  The app has been working well for many months.  I am using aerial imagery from 2017 as the reference basemap.  A short time ago the image supplier changed the URL to the ArcGIS Server site having this imagery.  Today, I discovered the app will not open due to the "missing" imagery.  I thought I could simply open the web map in the AGOL viewer, remove the imagery in the Table of Contents, and insert the imagery using the new URL, or select another basemap.  When I open the web map in the viewer, I receive an error "Basemap is not available.  Displaying the default basemap instead."  Instead of continuing to open the web map with it's remaining layers, the viewer creates a new 'My Map' with the default basemap instead.  None of the other layers are loaded.  Again, I was hoping the web map would load and I could simply update the image/basemap.  This does not seem to be the case.  I spent a lot of time on building and configuring this app, and I was hoping to avoid having to start over.  Any help would be appreciated.

[JayHodny · Accepted solution]

I found a post referring to the ArcGIS Online Assistant.  I was able to update the suspect basemap URL using the Assistant, which then allowed the web map to open, and I was able to move forward.

[JayHodny]

I meant to follow-up this thread back in June, my apologies.  I was never able to get the web map operational after using the Assistant.  I learned from Esri tech support that this utility is not supported by Esri, so use at your own risk.  I had to rebuild the web map.