Error on update to 18.03.1

I have the stock FP OS and try to update from 18.02.0 to 18.03.1
Twice in a row, I had an error after reboot, while the system was updating. Removing and reinserting the battery allowed me to reboot my phone, the update was not applied.

What do do?

A post was merged into an existing topic: Fairphone OS 18.03.1 release