One of our webinar infrastructure providers has experienced issues with Firefox 138. When using this browser version, some hosts and presenters in webinars may not see video streams from other participants.

Audio remains functional, and the browser still correctly broadcasts the user's video to other participants and to the webinar audience.

Firefox 139, launching on Tuesday May 27, 2025, will include a fix for this issue.
 

What happened?

The issue is caused by a bug introduced in Firefox 138. It has been escalated, and more status information can be found through Mozilla and Firefox support channels.

The bug has been resolved and the fix will be included in Firefox 139.
 

How to avoid the issue?

If you are hosting or speaking in a webinar using Firefox, we recommend using version 137 or upgrading to version 139 once it becomes available.
 

Does this affect the webinar audience?

No. Anyone joining webinars as an audience member will see the full webinar room in all browsers, including Firefox 138. The recommendation to switch browsers applies only to webinar hosts and presenters.
 

How to get more information?

We will keep this article updated with relevant information about the issue. If you have any questions, please reach out to our specialist team, who are standing by to assist you.

Last updated: Thursday, May 22, 12:45 CET.