I am doing my system maintenance with sudo bash -c "apt update && apt full-upgrade && apt autopurge && apt clean". Besides the standard Ubuntu repos, I also have a couple of ppa repositories which sometimes lag behind in support for the latest distribution.
Example: When Ubuntu 25.04 (Plucky) gets released, most ppa repos won't support it for a while, only the predecessor Oracular. Monitoring them is time-consuming, I'd rather switch over all of them to the newer release. But this breaks the update process with the following error:
Err:9 https://ppa.launchpadcontent.net/ubuntuhandbook1/mpv/ubuntu plucky Release
404 Not Found [IP: 185.125.190.80 443]
Get:10 https://repo.charm.sh/apt * InRelease
Error: The repository 'https://ppa.launchpadcontent.net/ubuntuhandbook1/mpv/ubuntu plucky Release' does not have a Release file.
Notice: Updating from such a repository can't be done securely, and is therefore disabled by default.
How can I force apt to ignore missing release files from these repos? I tried with
apt -o Acquire::Check-Valid-Until=false update
but this seems to work only for expired repos, not for those missing.
Please note that this is not about 25.04, which will be released in the next few hours, but a general question and therefore shouldn't violate the rules.
