Incident report: 50% of ActiveSync connections failed..

On Sunday 2025-06-15 one of the Kolab now ActiveSync servers were getting overloaded and got stuck on failed jobs. In turn, about 50% of the ActiveSync jobs were failing – leading to some ActiveSync users loosing the connections to Outlook or to their mobile devices.

While the healthcheck is actively monitoring on the the webserver process (httpd) of these front end servers, the problem was with the php-fpm process which ran out of memory and died. This resulted in php requests failing. The healthcheck continued to succeed, as the httpd process was still active on that individual backend.

The issue was realized and the root cause was fast found on Tuesday morning early, and at this time all servers and services are running with no issues.

We apologize for any inconvenience that this may have caused.