Today a Business Central Cloud Production Instance is still upgrading despite it is way past maintenance window and the customer can't open the Database. It would be nice if I could cancel that Upgrade Process in the Admin Center when it is outside of the maintenance window and still running so the customer could work and the upgrade problem could be transferred to Microsoft Support.
Ideas Administrator

Thank you for this suggestion! 
We are trying to address this challenge in other ways. The way the upgrade routine is implemented today, may require considerable time (possibly hours for large databases) for an environment to be re-activated on the previous version if we cancel update in the middle (internally we use point-in-time restore operation in such cases). 
So instead of allowing to cancel updates, we've already implemented several other improvements to considerably reduce the number of environments updates running out of the maintenance window (scheduling-wise and performance-wise). Our telemetry shows that there are very few updates which have this challenge now and for these few cases the update is completed or rolled back within several minutes, up to 30 min.  

Best regards,
Dmitry Chadayev
Business Central Team