The time window (within which planned system maintenance can occur) is weekly, on Tuesday between 17:00 and 18:00 (local time in Amsterdam, Netherlands).
Users are informed with a notification in ATS about the planned maintenance. ATS is not available during maintenance. All users are logged out and all running tests are canceled. Schedules and CI/CD are disabled during maintenance as well.
There is a notification after maintenance, which shows the changes made.
Maintenance for fixing major issues can occur anytime outside the maintenance window. Any downtime will be announced as early as possible.