In the 6.2.0 release, the offline and warmupseconds options of the admin?op=update command are unsupported.

In previous releases, these options were essentially deprecated. You could issue a admin?op=update command with the offline or the warmupseconds options, and the MDEX Engine would ignore the commands, issue a warning, and continue processing the update.

In 6.2.0, support for the offline and warmupseconds options has been entirely removed. The MDEX Engine no longer issues a warning and stops processing the update if you specify them.