Hi @janus_zonstraal
Thank you for the answer.
I deleted the complete 'forum' folder after a failed update and restored my ftp files from phpBB 3.3.4
The forum now works.
There is also a 'io.lock.lock' file in the 'store' folder from June 3, 2021 as well as a 'composer.lock' in the root 'forum' folder from April 27, 2021.
So I now have the situation as before the update.
Can you explain to me how to do the 'full method' update? (perhaps a link to the instructions).
Do you mean these instructions?
https://www.phpbb.com/support/docs/en/3 ... date_full/
btw: I didn't find the 'installer' file, from the 'store' folder?
The install folder has been removed.