M2.2.3 - backend is half dead after rollback of system backup
upfront: I'm very new to Magento but have a bit of experience with the Linux and am not afraid of the command line. Magento wise I haven't much of an understanding of manz details
I have a pretty fresh test installation of M2.2.3. Tried to install a Chinese language pack via the command line and after that failed I did 2 rollbacks of existing backups.
1st rollback of a database backup seemed to work backend wise but as it looked as if there where still some breadcrumbs left on the OS level, so I did a rollback of a system backup done right after installation. The store is still online apparently is functional and I can login to my backend.
Once logged in I can not get anywhere passed the Dashboard. clicking on anything else in the backend at best initiates the hourglass to indicate something was processing but nothing ever happens beyond that. So practically my store looks alive but actually is dead.
is that something to expect by default? If so, what's the way to effectively and reliably make system backups of a Magento system?
Any fix that can be applied here to get back to a working store?
As mentioned I have not much pre-existing experience, so that'd be a reason why I don't even have an idea where to even look at.
EDIT: I picked up somewhere this may be a problem with my Session and one could solve this by delecting something in the ~/var directory of my magento installation. But what exactly? could imagine the content of ~/var/cache or content of ~/var/page_cache. Any pointers?