When you login to SAP GUI and you get the error SAP System Message N. The error usually indicates that database stopped in a unexpected way. Usually you can't login
A common cause of this issue could be caused by a SAN Volume name changed.
Make sure there is no offline backup running on the system, the system won't allow you to login. When backup finishes you can login as always.
First check that: * In SAPMMC all the instances and processes are in green. * Check dev_w0 . * Search for error in database logs. * ABAP WP Table.
If you see the following error in ABAP WP Table, probably someone changed the SAN volume name.
No 0, type=DIa, pid 056, Status= Ended, reason=blank, start=no, Err=126, sem=blank, cup=0, time=37175,program=SAPLTHFB, client=000,user=sapsys, action=commit
Try to restart from SAPMMC, if not possible go to solution 2.
Since there is a problem with the database you will be forced to shutdown SAP and the database using ssh, then reboot the server. Start the database and SAP normally from SAPMMC.