Having exactly same issue, same output also uninstalled all plugins before upgrade.
sed: cannot rename /etc/apt/sedo4GYvd: Operation not permitted
run-parts: /tmp/tmp.fXgHfrsxgw/pre.d/20-apt-update-source-list exited with return code 4
Also notice
omv-mkconf php5fpm
Unknown script, /usr/share/openmediavault/mkconf/php5fpm not found.