The following error is being shown when you login to the Plesk Panel:
ERROR: Call to a member function getAttribute() on a non-object (DefPackageMng.php:231)
defpackagemng.xml located in
%plesk_dir%\\admin\\db is absent. It was being deleted manually or by some utility.
Run command below in CMD to regenerate the
`"%plesk_bin%\\defpackagemng.exe" --get --force`