@Friendica Support

After updating to 2019.12 Friendi.ca stopped working. As it turned out the problem was too may semaphores. Friendica failed with

NOTICE: PHP message: PHP Warning: sem_get(): failed for key 0x6602b303: No space left on device in /path/to/friendica/src/Core/Lock/SemaphoreLock.php on line 41]

I found the command line

for whatever in `ipcs -s | awk '{print $2}'`; do ipcrm -s $whatever; done

which fixed the issue for me. My hoster is Uberspace and I don't know if this information is of use to anybody, so just in case.