What is this error?

This error occurs when a session executing a DDL tries to put a lock on a table is already locked by other session.
This error can also occur when a replication transaction tries to put a lock on a table that is already locked by a local transaction. (In this case, you can find the error message in $ALTIBASE_HOME/trc/altibase_rp.log)

How to confirm this condition?

Users will need to validate to make sure that in fact there is a lock on the target table by another session.
To learn more about how to check session conditions, please review this content.

How to resolve this case?

There are two ways to resolve this problem.
First, terminate session that has a lock on the target table. (See this page.)
Second option is simply to wait for a while. Lock can be unlocked when users explicitly execute a commit or rollback.