Symptoms

"DS not found" error is thrown for domain service related tasks, for example:
"Disable domain service (ds_id=<ds_id>, hd_id=<hd_id>) on host '<hostname>' (host_id=<host_id>)" can fail with this error.
 

Cause

This error is caused by the fact, that some operations were scheduled for a nonexistent domain service. Such kind of inconsistencies may appear due to manual database intervention or changing PEM tasks processing order - canceling and rescheduling related tasks. Also there is an issue with PEM (bug#103891, scheduled to be fixed in a hotfix for 2.6.5) which can lead to such state.
 

Resolution

As these tasks are scheduled for nonexistent domain service, they can be canceled.