Error ORA-235 occurred during an un-locked control file transaction

Error ORA-235 occurred during an un-locked control file transaction.  This error can be ignored.  The control file transaction will be retried. RFS[2]: Opened log for thread 2 sequence 40781 dbid 2440526278 branch 1089779374 RFS[3]: Opened log for thread 1 sequence 40695 dbid 2440526278 branch 1089779374 RFS[4]: Opened log for thread 1 sequence 40693 dbid 2440526278 branch 1089779374 RFS[1]: Opened log for thread 2 sequence 40779 dbid 2440526278 branch 1089779374 Tue Mar 21 04:11:38 2023 Archived Log entry 66837 added for thread 2 sequence 40781 rlc 1089779374 ID 0x0 dest 2: Tue Mar 21 04:11:40 2023 Archived Log entry 66838 added for thread 1 sequence 40693 rlc 1089779374 ID 0x0 dest 2: Tue Mar 21 04:11:40 2023 Archived Log entry 66840 added for thread 1 sequence 40695 rlc 1089779374 ID 0x0 dest 2: Tue Mar 21 04:11:43 2023

As already advised in the alert log file, along with this error message, this error can be just ignored. The reason of this error is multiple processes trying to get hold the lock of a controlfile section that they need during their operation. For example, I observed above messages in the alert log file of a physical standby database for which I was trying to resolve archived log gap. When this error was logged, I also observed sessions connected to physical standby database from rman.

SID        USERNAME     MACHINE        MODULE ---------- -------------------- ------------- ------------------------------------------- 596         SYS                    myhost               rman@myhost (TNS V1-V3) 791         SYS                    myhost               rman@myhost (TNS V1-V3)

For RMAN’s case, If this is causing you trouble by causing delay to some work, you may simply stop/kill the RMAN sessions you see connected