I had the same issue with a root server from Strato. For analysis I have executed the script /etc/cron.daily/pleskupdate directly. Most time the response code was 0, so there was not a directly problem with it. But when I have used
run-parts --report /etc/cron.daily, what is used by the server to start automatically all scripts in this directory, I have received the annoying mail with the info "run-parts: /etc/cron.daily/pleskupdate exited with return code 1". A directly start of /etc/cron.daily/pleskupdate afterwards have then also finished with return code 1.
I have noticed the message "Update operation was locked by another update process." in the autoinstaller3.log. Maybe there are some other scripts in /etc/cron.daily, that are blocking something for a short time?!
So I have added a simple sleep to the pleskupdate script, what at first glance solved the issue on my server.
This is the current script:
Bash:
#!/bin/sh
# Plesk autoinstaller
sleep 120
/usr/local/psa/admin/sbin/autoinstaller --select-product-id plesk --select-release-current --install-component base >/dev/null 2>&1