An unexpected error has occurred. [LFF502-UnexpectedError]

Details:
URL: 
Error: UnexpectedError
Date: 6/4/2018 7:37:37 PM (Central Standard Time)
HTTP Status Code: 500
Business Process ID: 222
Instance ID: 12571
Business Process Name: Grant Checklist

Stack Trace:
Caught exception: Laserfiche.Forms.CommonUtils.Exceptions.LFFormsException
Message: An unexpected error has occurred. [LFF502-UnexpectedError]


Inner exception: System.Collections.Generic.KeyNotFoundException
Message: The given key was not present in the dictionary.
   at System.ThrowHelper.ThrowKeyNotFoundException()
   at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
   at Laserfiche.Forms.Routing.Gateway.AddNewConvergingProcessInstance(Int32 instanceId, SequenceFlow seqFlow, IRoutingContext routingContext)
   at Laserfiche.Forms.Routing.Gateway.GetAllSubsequentSteps(Int32 instanceId, Int32 processId, Int32 sourceStepId, IRoutingContext routingContext)
   at Laserfiche.Forms.Routing.InclusiveGateway.TryMerge(cf_bp_worker_instances processInstance, IRoutingContext routingContext)
   at Laserfiche.Forms.Routing.FlowObject.UpdateInclusiveMergeSteps(cf_bp_worker_instances instanceInMergeContext, IEnumerable`1 inclMergeSteps, IRoutingContext routingContext)
   at Laserfiche.Forms.Routing.Gateway.Execute(Int32 instanceId, IRoutingContext routingContext)
   at Laserfiche.Forms.Routing.RoutingDispatcher.ExecuteSteps()