Error 2 connecting to unix socket: /omd/sites/dev/tmp/run/redis

[peterge (Peter Gerhards)]

CMK version: 2.1.0p19
OS version: RAW - Docker
Error message:
Started at: 12:32:53. Finished at: 12:32:53.
Error 2 connecting to unix socket: /omd/sites/dev/tmp/run/redis. No such file or directory.

I face this error message when activating changes via REST API. This is what the API prints as response ( | awk -F"=" '/^xxx-status_code/ {print $2}'):

Why does this happen?

When I click on Activate Changes, it just works every time. Adding a sleep command before the curl request for Activation is sent does not change anything.
docker compose exec checkmk cat /omd/sites/dev/tmp/run/redis does print this the whole time during deploy and during starting CheckMK container:
cat: /omd/sites/dev/tmp/run/redis: No such device or address

I don’t understand what the container is waiting for? This seems very strange…
This error does print like one out of three times deploying this container from scratch - I do not get why it does sometimes work, and it doesn’t in other cases…

[peterge (Peter Gerhards)]

Okay, I still dont get why I am facing this problem, but I found a very dirty workaround which works for me:

I just needed to execute omd restart {site} to restart apache to load a icon in the webgui. I just found that I can achive this with omd restart {site} apache too, without touching redis at all.