[ovirt-users] mantenance mode error

[nicola.gentile.to]

hello,
I must put in maintenance mode the node of ovirt but returns the 
following error (by admin web page):

Error while executing action: Cannot switch Host to Maintenance mode. 
Host has asynchronous running tasks,
wait for operation to complete and retry.

I have checked the log file engine.log and returns the following errors:

2016-06-30 13:31:35,688 INFO 
[org.ovirt.engine.core.bll.MaintenanceNumberOfVdssCommand] (default 
task-47) [5f3d36f7] Lock Acquired to object 
'EngineLock:{exclusiveLocks='null', 
sharedLocks='[00000001-0001-0001-0001-00000000037d=<POOL, 
ACTION_TYPE_FAILED_OBJECT_LOCKED>]'}'
2016-06-30 13:31:35,692 WARN 
[org.ovirt.engine.core.bll.MaintenanceNumberOfVdssCommand] (default 
task-47) [5f3d36f7] CanDoAction of action 'MaintenanceNumberOfVdss' 
failed for user admin at internal. Reasons: 
VAR__TYPE__HOST,VAR__ACTION__MAINTENANCE,VDS_CANNOT_MAINTENANCE_SPM_WITH_RUNNING_TASKS
2016-06-30 13:31:35,692 INFO 
[org.ovirt.engine.core.bll.MaintenanceNumberOfVdssCommand] (default 
task-47) [5f3d36f7] Lock freed to object 
'EngineLock:{exclusiveLocks='null', 
sharedLocks='[00000001-0001-0001-0001-00000000037d=<POOL, 
ACTION_TYPE_FAILED_OBJECT_LOCKED>]'}'

how can I do to see if there are tasks?

What can i do for resolve the problem?

Thanks in advance

Nicola