Unfortunately the suggestions in the KB don't fix the problem.
The dump of autoinstaller3.log after trying to get to Home > Tools & Settings > Updates and Upgrades
[2017-03-11 10:04:55.184470]
Plesk Installer 3.20.17 (built on 2016-10-07 16:13 svn rev. 349581) started at (timezone CET) Sat...
Unfortunately no luck with both the solutions. The ./plesk-installer command is working without problems.
Coud the problem be related to https://kb.plesk.com/en/122949 ?
Thank you for your replay.
Unfortunately we still experience the problem. After Home > Tools & Settings > Updates and Upgrades we ge a screen with language-choice and admin username and password fields.
When we fill in the correct credentials the error message (Can't connect to backend: No such...
TITLE:
Can't connect to backend: No such file or directory message in Plesk Update (8447/summary.html) page
PRODUCT, VERSION, OPERATING SYSTEM, ARCHITECTURE:
OS CentOS 6.5 (Final) Plesk Onyx 17.0.17 Update #18
PROBLEM DESCRIPTION:
After the upgrade from Plesk 12.5 to 17 the update screen...
After the update from 12.5 to 17 we have the same issue.
Both solutions (plesk installer --select-release-current --reinstall-patch --upgrade-installed-components) and (https://kb.plesk.com/en/122949) did not solve the problem. Can we try something else?