Install on Debian 11: Failed to create shared memory object "FTL-lock": Permission denied

Expected Behaviour:

After installation, Pihole-FTL should be up and running.

Actual Behaviour:

Pihole isinstalled without error message. However, when load the webinterface, i get the message "DNS service not running", FTL icon is also red.

In /var/log/pihole-FTL.log, i see the message:

[2021-10-10 15:36:39.377 36778M] ########## FTL started on fruchtzwerg! ##########
[2021-10-10 15:36:39.378 36778M] FTL branch: master
[2021-10-10 15:36:39.378 36778M] FTL version: v5.10.2
[2021-10-10 15:36:39.378 36778M] FTL commit: 2f2b5bf6
[2021-10-10 15:36:39.378 36778M] FTL date: 2021-09-30 20:55:27 +0100
[2021-10-10 15:36:39.378 36778M] FTL user: pihole
[2021-10-10 15:36:39.378 36778M] Compiled for aarch64 (compiled on CI) using aarch64-linux-gnu-gcc (Debian 6.3.0-18) 6.3.0 20170516
[2021-10-10 15:36:39.378 36778M] FATAL: create_shm(): Failed to create shared memory object "FTL-lock": Permission denied
[2021-10-10 15:36:39.378 36778M] Initialization of shared memory failed.

Debug Token:

https://tricorder.pi-hole.net/8sEtGmnp/

After re-install the complete image, installation and function is working fine now. I have no idea what was wrong with the previous installation.

From my side of view, we can close this request, but it would be nice if there could be a more verbose hint in the logfile, what file or directory needs the right privileges.

This is not straightforward to answer. Typically it will be the directory /dev/shm but operating systems are free to chose whatever they prefer and I'm not aware if we can get that reliably without too much overhead.

Something was definitely wrong with the system, maybe shared memory wasn't initialized correctly.