Hi,
because you forgot to upgrade also modules
Install new versions for J3.x GK4.
...of course we suggest to use GK5 edition not old GK4, but.... it request new settings from you.
p.s.
When you upgrade your Joomla (or any other CMS) you should always upgrade also all modules and plugins to be sure they will work fine !!
Miłej zabawy.