REST - ArcGIS Javascript Preview not Working after upgrade to 10.4.1

Question

I just upgraded our Test Servers from 10.3.1 to 10.4.1.  After the upgrade the f=jsapi output format is not working for the various map services in the Rest Directories whether going through the Web Adaptor address or directly to the site inside the firewall.  Has anyone experienced a similar issue?  The Map Services work fine in ArcGIS Desktop, AGOL, etc., but not in the ArcGIS JavaScript Preview.

Now the javascript window does not "activate".  Mostly just a blank screen is shown under the Map Service name.  I saw some old documentation about caching of the Rest directory, but nothing recent.

Thanks

JeffSmith · Accepted Answer

It sounds like the Javascript API URL may not have updated successfully or may have become corrupt during the upgrade process.  I'd login to the Server Admin Directory and double-check it.  For a new ArcGIS Server 10.4.1 installation, the Javascript api urls are configured like this: