On September 21, ZennoBrowser 1.20.3 was released with the Chromium 153 engine. That same day, users reported on the forum that profiles would not launch. For example, starting one from ZennoPoster returned a “Failed to open connection” error. Rolling back was not possible. According to support, updating migrates profiles to the new engine, after which they will no longer launch on the previous version. Support also said the update rollout could not be paused: doing so would have stopped users whose new version was already working, and there were more of them.
On September 24, the company apologized and said the issue affected Windows Server Datacenter 2019 and some versions of Windows 10. A 1.20.4 hotfix was released the same day. According to ZennoLab, the cause was a crash in one of the Chromium components that prevented profiles from starting. Users in the thread confirmed that profiles worked again after installing 1.20.4. About three days passed between the first reports and the fix.
If you are stuck on 1.20.3, update via “Settings → Check for updates”; 1.21.1 is currently the latest version. Version rollback is still unavailable in ZennoBrowser: on October 7, support reiterated this in the 1.21.1 thread.
