@ Subflow error in Log

Hi,

I am new to Workflow. I have activated one standard workflow. It has a subflow.

After execute transaction Event has triggered in SWEL. but in log @ Subflow spot error there.

We maintained users at transaction level. Based on that workflow should send mail a to that users.

Here i need to explain about this subflow does not have any events, inside it has 2 single tasks which are all background tasks and one condition step.

In error Log shows error at Subflow task.

Why Error generated? What to do for this?

Thanks in Advance,

Soniya