I have two different calendar setups where I was successfully importing my Outlook events into Google Calendar using the ICS feed URL. Both calendars were working perfectly for several months until recently.
Now one of my calendars just stopped updating in Google Calendar while the other one continues to work normally. I can still access the calendar data through the HTML link which displays everything correctly, but the ICS feed seems broken.
What I’ve tried so far:
Completely deleted the calendar from Google and re-added it
Disabled calendar sharing in Outlook web settings and re-enabled it
Generated a new ICS link and tried importing that
Waited several days thinking it might be a temporary issue
Does anyone know what might cause this kind of selective failure? Any other troubleshooting steps I should try?
Same thing happened to me six months ago. Turned out Microsoft’s calendar permissions got corrupted somehow. The ICS link generated fine but had zero event data, even though the HTML version showed everything. Here’s what fixed it: went into Outlook online, moved all events to another calendar temporarily, then deleted the broken calendar completely and made a new one. Set up sharing again and grabbed a fresh ICS feed. Microsoft’s got backend issues where calendar metadata gets stuck but the calendar looks normal. Since your HTML link works, the data’s there - something’s just blocking the ICS export. Before nuking it though, try opening the ICS URL directly in your browser. You’ll see if it’s actually returning calendar data or just an empty feed. That’ll tell you if it’s a generation problem or Google can’t import it.
Had this exact issue last year with my work calendar. Microsoft changed some security settings that broke existing ICS feeds without telling anyone.
Try this: go to your Outlook web app, find the broken calendar, and check if sharing permissions are still correct. They sometimes reset to “private” automatically.
If that doesn’t work, delete the old ICS link and generate a new one. Don’t copy the existing URL - go through the whole sharing process again.
Also check if you hit quota limits on Google Calendar’s side. Google has undocumented limits on external calendar feeds and sometimes randomly stops syncing one.
Since your other calendar works, it’s not a connectivity issue. Usually means either permissions changed or Microsoft silently killed that feed URL.