I think I found a bug that causes workflows to error with the following log entry:
Nintex.Workflow.NWActionExecutionException: Error in task. ---> System.NullReferenceException: Object reference not set to an instance of an object. at Nintex.Workflow.HumanApproval.Message.AddAttachmentToEmail(INWWorkflowContext context, NWContextDataCollection contextData, Func`1 getAttachmentList, AttachmentCollection attachmentCollection) at Nintex.Workflow.HumanApproval.Message.SendEmail(String subject, User user, NWWorkflowContext context, NWContextDataCollection ctxData, MailAddressCollection toAddresses) at Nintex.Workflow.HumanApproval.Message.Send(Approver approver, Message persistTo) at Nintex.Workflow.Activities.SendReminderActivity.Execute(ActivityExecutionContext executionContext) at System.Workflow.ComponentModel.ActivityExecutor`1.Execute(T activity, ActivityExecutionContext executionContext) at System.Workflow.ComponentModel.ActivityExecutorOperation.Run(IWorkflowCoreRuntime workflowCoreRuntime) at System.Workflow.Runtime.Scheduler.Run() --- End of inner exception stack trace --- (Build:3300)
The error is triggered when the following conditions are met:
- The workflow is running on a list with attachments disabled.
- The workflow has a task with reminders configured.
- The 'Attach file' checkbox in the reminders tab is checked.
- A reminder for the above task is sent.