Sorry my mistake it was the auanasgheps script I tried and it gave the above error messages. OMV6.
Are you sure you're running the latest version?
v3.1 supports Debian11/OMV6 and will also install python3-markdown (if not found).
Also:
Please update your config file to the latest version. The current file is not compatible with this script!
Means you have to move your old configs to the new script-config.sh because I added new variables.