Default AFX fulfillment Error

Hi,

We are @7.0.1. 

We are using role based provisioning where user gets group access based on the role he/she assigned to. Group provisioning is being handled through default AFX fulfilment. But sometimes we are seeing below error when fulfillment workflow processes request for adding account to groups.

Exception caught during script evaluation. Script 'Node - Available Asynchronous', ScriptID=3:WPDS, JobID=73665:WPDS, JobRef='6722', ProcessRef='acm$crafxsub', JobRowVersion =3, NodeName='AFX Fulfillment Handler', JobNodeID=1036267:WPDS, WorkItem=812891:WPDS:1, FIFO=404943. Exception was: com.workpoint.common.exception.ScriptEngineException: java.lang.NullPointerException Error occurred in Statement #1 in Script ID 3:WPDS, Script Name = 'Node - Available Asynchronous', Script type = 'Action'. Job ID = 73665:WPDS, Process Ref = 'acm$crafxsub', Node Name = 'AFX Fulfillment Handler', WorkItem = 812891:WPDS:1.  

Error is coming similar in most of the cases and only changes are JobID,Workiteam, JobRef etc. 

What could cause this error?