Binary log shows backup fails with “Worker process Xu has exited prematurely” but prior to this we see the job message “TaskID 1u Failed to acquire lock on the VM disk(s)” as seen below.
Job Message 2015/03/01 09:04:37 51 Data Plugin SRVDC03 TaskID 1u Guest within VM 'SRVDB01' uuid '4221d9b3-4443-869c-cdea-87538faf95f5' will not be quiesced
Information 2015/03/01 09:05:05 73 Data Plugin SRVDC03 TaskID 1u Retrieved information about VM files successfully
Job Message 2015/03/01 09:05:05 51 Data Plugin SRVDC03 TaskID 1u Failed to acquire lock on the VM disk(s)
Error 2015/03/01 09:05:05 51 Data Plugin SRVDC03 Worker process 1u has exited prematurely
De-registration and re-registration of VMs in vCenter.
Note sometimes we also need to recreate the backup set for the job.