Can you confirm  if you create  test library for instance (File library), save the configuration.  If you modify the drive configuration against that test file library afterwards does that also crash CRS?

If the answer is no, perhaps there is something in the configuration of the existing library that the CRS is not agreeing with and I would just use omnidownload to download the lib and drive config to file (so you have a backup) then delete the library and drives and recreate it with the exact same naming convention so existing saved backups will not be impacted

Hello,

I've created a test File Library with 2 drives, changed the configuration in one of the drives and CRS crashed again.

Which confirms it is not the library itself.  Perhaps invalid entry in cell_info.  Best we get a case logged with support to confirm

Unfortunately we can't open a case with support team, as we are in the process of transferring some old licenses (but not for a couple of months yet) and adding new ones we've bought, so we currently use the evaluation license.

Really difficult to zero in on issue this way.  What you can try is make a copy of the cell_info file(so you can revert back), then edit the cell_info and keep only the cell manager and media agent client with the library config in the cell.  Then launch the GUI and see if it still crashes when modifying a drive

If it doesn't an entry in cell_info is causing this

I tried what you've suggested but nothing happened.

I even uninstalled and re-installed Data Protector (fortunately it's a new environment with not so many clients yet, so I was able to do that) and the problem still exists.

When I made a change in the configuration of one of the drives and while the CRS is crashed, I tried to change something in the configuration of another drive and got the error 

I don't know if this is a normal behavior when the CRS is down or if it's something that can help you identify the problem...

That message is most likely seen only because the CRS connection is lost. You can even see "SCSI Library" as the Device Type which is basically the POLICY statement in the library configuration.

One interesting thing is you are seeing error "[5] Access is denied". My question now is: is the CRS really crashing or is it like the error suggests a permission issue?

I thought about the "access denied" message, but I can't figure out where the problem could be. CRS service runs with an administrator account, with all the rights needed and every time, I get the error "The Data Protector CRS service terminated unexpectedly.  It has done this x time(s)." in the server's System log.
More specifically the account used for CRS service is a local admin, domain admin and has the following rights:

• Impersonate a client after authentication.
• Log on as a service.
• Replace a process level token

Is there something I'm missing here?

Please double check this:

Support Tip: Properties of a Windows DP service account

I gave all the permissions/rights mentioned in the Support Tip explicitly to the account used for CRS (although this account was already in the Local Administrators group as long as in the Domain Administrators group).
Nothing changed, I get the same message (the one with the "Access denied").

It's really frustrating!