ORA-00261: log string of thread string is being archived or modified

ORA-00261: log string of thread string is being archived or modified
Cause: The log is either being archived by another process or an administrative  command is
modifying the log. Operations that modify the log include clearing,  adding a member, dropping a member, renaming a member, and dropping the log.
Action: Wait for the current operation to complete and try again.