Hi Mitchems,
What fixed this for me is using the relative path to point to the old plugins folder:
The old version was at https:/adserver.domain.com/revive
The new version was at https:/adserver.domain.com/revive-new
I tried absolute paths, relative paths but in the end I had to use a relative path AND designate the path starts in the folder above.
../revive
That solved the issue for me. Hope this helps!