Oracle 11gR2: ORA-01102: cannot mount database in EXCLUSIVE mode I am running Oracle 11gR2 on an AIX box.  I did a rename database and change DB ID using NID.  I can restart db in a nomount mode, but I can not mount it by the following error.

ORA-01102: cannot mount database in EXCLUSIVE mode
ALTER DATABASE OPEN RESETLOGS
*
ERROR at line 1:
ORA-01507: database not mounted


I started DB by using a new pfile.  I notice that the NID utility did not change the old DB folder names in ASM.  So this rename database effort will not be perfect.

I have already removed some easy things when I Googled this error, such as removing the lk* files under $ORACLE_HOME/dbs.

Any suggestions for me to start the database after the renaming command of NID?

Thank you so much!
ORA-01102 cannot mount database in EXCLUSIVE mode
  
  Cause: Some other instance has the database mounted exclusive or shared.
  Action: Shut down the other instance or mount in a compatible mode.


Find whether you have any running Oracle process.


$ ps -ef | grep smon


Kill the process then try to start again.

Since I dont have the procedure which you have followed to perform DB rename and DBID change I can not say whether there is problem with your procedure. 

I would recommend to follow Oracle Knowledge Document to perform such task. 
How to Change the DBID and the DBNAME by using NID