SSH Access denied after upgrade to 12.1 (from 11.8.1)


First, I apologize if I’ve missed the category, (although the issue I saw popped up after upgrade). Note that this post isn’t bug-report per-se, more than guide for future readers.

I have upgraded our GitLab (CE) from

From 11.8.1-ce.0 to 11.11.5-ce.0
and then from 11.11.5-ce.0 to 12.1.0-ce.0.

I also upgraded the PG to 10.7 and Prometheus as instructed in logs.

Everything went smoothly, however few of us noticed error messages such as
“Access denied”, “Fatal error: Server sent disconnect message”, “Too many authentication failures”.

Luckily it can be fixed quickly by generating new SSH key.

Per GitLab site The minimum key size is 1024.

Funny thing is that all of us which have experienced the problems had keys of 1023 bits (per Pageant), which caused this problem / SSH key not to be accepted by GitLab