Unable to login to Plesk:
In /var/log/plesk/panel.log following error can be found:
[2017-04-10 20:46:02] ERR [panel] Execution vhosts-traffic-monitor.386 has failed with exit code 127, stdout: , stderr: sh: /usr/local/psa/admin/bin/vhosts-traffic-monitor.386: No such file or directory
Corrupted traffic monitor extension.
1. Remove traffic monitor extension:
# /usr/local/psa/bin/extension -u traffic-monitor The extension was successfully removed.
2. Install it from Extention catalog: Plesk > Extensions > Extensions Catalog > Domain Traffic Monitor 1.2