At the beginning of this thread your wrote todo "# plesk installer --select-release-current --reinstall-patch --upgrade-installed-components" with the known error. What's right now?
Yes, i did so, but it doesn't help. After patching i got "2018-06-29 10:52:27 ERROR: E:Can't find a source to download version '8+deb8u11' of 'base-files:amd64'" when updating with UI.