I have installed Esri Maps for SharePoint and configured every thing. It was working before 2 weeks.
Now when I enter the page it ask me to login (Click here to sign in to ArcGIS.) and then I got following error:
If you go to /portaladmin/security/oauth/getAppInfo and then enter mapsForSharePoint in the App ID parameter, what output do you get? FYI this will include hostnames so take that into consideration before posting the output. If the public Portal URL isn't in the list of redirect URI's, that may be the problem.
I get an ArcGIS page that says "We're sorry, the page you're looking for can't be found."
I should mention that I am using my AGOL subscription for my maps for sharepoint, I do not have Portal for ArcGIS installed locally. It was working perfectly since I configured it months ago until a couple weeks ago.
Both JQuinn-esristaff and I are more familiar with Portal for ArcGIS, than ArcGIS Online. I shared this thread to the ArcGIS Maps for Office forum, hoping others might be able to assist.
I suggest you contact Esri Tech Support to open an incident as they can best help investigate your issue.
Hope this helps,