PROBLEM:

Users are getting below error, while trying to connect to the database.

ERROR:
ORA-09925: Unable to create audit trail file
Linux-ia64 Error: 28: No space left on device
Additional information: 9925
ORA-01075: you are currently logged on

SOLUTION:

The error occurs , because the mount point where audit logs are written is filled.

check the mount point :

We can see that mount point is filled, so database is not able to write audit logs in adump location.

To fix this, clear space from that mount point And make sure free space is available for the audit logs.

Once space is available, user can connect easily.