We are using Zoom ISV with service accounts and dummy users.
Normally, anyone who opens the start_url becomes the host without logging in.
This has been working correctly for years.
Starting from early December 2025, we found that some start_url links
(around 30 meetings) suddenly stopped working. When opening the start_url,
Zoom shows this error:
“You cannot start the meeting because it is hosted by another user.”
Other start_url links generated the same day still work properly.
This means the problem is not on our system side — it seems certain ZAK
tokens generated via API were invalidated or rejected by Zoom backend.
We suspect an internal issue with ZAK validation for ISV.
Example problematic meeting ID:- 86580082526
We can provide the full start_url privately via DM.
Please help investigate why only some ZAK-based start_url links were rejected.
This issue affects our production system and customers cannot start meetings.
Thank you.