Debian/Ubuntu system update shows a warning:
Fetched 17.5 kB in 2s (6082 B/s)
Reading package lists... Done
N: Ignoring file 'plesk.list.ai_back' in directory
'/etc/apt/sources.list.d/' as it has an invalid filename extension
W: Duplicate sources.list entry
W: You may want to run apt-get update to correct these problems
The following warning appears during microupdate installation or running
CONFIG_TEXT:W: Target Packages (all/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list.d/50sw_autoinstaller.list:4 and /etc/apt/sources.list.d/plesk-migrator.list:1
This is a Plesk bug with ID PPPM-6049 that is planned to be fixed in future updates.
Until the issue is permanently fixed, the warning can be safely ignored.
Nevertheless, the following workaround can be performed to get rid of the warning: