[pgpool-general: 699] SR+load balance: Cannot execute SELECT FOR UPDATE in a read-only transaction

[Isengard]

Hi

My standby server is logging this error:
> Error: cannot execute SELECT FOR UPDATE in a read-only transaction
> SELECT * FROM QRTZ_LOCKS WHERE LOCK_NAME = $1 FOR UPDATE;

Any idea on how/why pgpool is sending a "SELECT..FOR UPDATE" to standby?

It seems the query is not inside a function, at least the error
message does not show that.
It's a third-party software, so I do not have access to the source-code.