Timer Execution fails

Timer Execution fails

Does anyone know what the error below means and how to overcome it?

Timer getSiteAddresses error (inside action 'getSiteAddresses'). Timer duration = 147 secs:"OSADMIN_DEV1".ossys_user_t9 with key 0 was not found [retry 1 of 3 scheduled]

Is that a timer of your own build code or of the platform?
Anyway, the error message is clear: the timer tries to select a record in ossys_user_t9 with id = 0 and that record doesn't exist.
An id=0 means that probably you passed a NullIdentifier as a parameter.
Check the parameters of the call to that getSiteAddress action and the parameters of the query.

(if the code this ok, you can debug the timer action and confirm the values in real time)
Are you using the "default" Get actions (the ones in the entities themselves)? They thrown an exception with precisely that error message (<something> with key 0 was not found) when you pass them a value of 0.
No we are not using the "default" Get Actions.  Interestingly, this is happening on all of the Timers I have created?
They are all calling Web Services if that makes a difference
An action that was being called by the Timer was trying to use session.id.  I have corrected this and all Timers now run as expected.

Thanks for everyones help.