How do I set up a Process to send a task due date alert?

You can create a Process Definition aimed at Task module to accomplish this. Create a Start Event that applies to all Tasks that have a Status not equal to "Completed." Then create a Wait Event with settings equal to "Due Date minus 1 Day." Finally, create a Send Message Event with the template email reminder. See below for how it should look:

I have set it up as you have shown and created a due date one day past now.  It has passed the time the alert should have sent and I have still received nothing, but if I look at Process Management I do see it is In Progress.

Since the date occurred in the past, it will not trigger. I don't think it can retroactively trigger something that has already occured. Try to test it using minute intervals. Make a Task due, for example, at 2:45PM and make the wait event trigger an email 5 minutes before it's Due. That way, you will know for sure if it worked.

I will try shorter intervals, but the time is not in the past.  It was before 1:30pm here and the task was due at 1:30PM the next day.

Gotcha. With the 1 Day interval, I'm not sure if it's calculated exactly by 24 hours. It could be scheduled differently, like triggered the midnight before, regardless of time. I'm not certain though. Let me know if the minute works. Also, is your email setup and working? That could also be a factor.

Our email functions work fine. It just seems to be the SugarCRM timing operations that are not consistent.

It appears that it is still not working.  I have run through the "Troubleshooting the Wait Event" document with no success.  I have a ticket in to SugarCRM support on this issue.  

Ok, the 1 day task alert finally sent.  I set the task to be due at 2pm tomorrow.  The alert sent at 2:15.  There is an "issue" with the email scheduler (as confirmed by a previous SugarCRM support case I had) that may cause the alert to have a significant delay.  SugarCRM had recommended that I use the End Process icon to send the email alert rather than the Email action item.  However, that did not work for me in this case.  I will continue to experiment, but for a 1-day alert, a 15-minute delay may be ok.  Thanks for all of your help!

Ok, the 1 day task alert finally sent.  I set the task to be due at 2pm tomorrow.  The alert sent at 2:15.  There is an "issue" with the email scheduler (as confirmed by a previous SugarCRM support case I had) that may cause the alert to have a significant delay.  SugarCRM had recommended that I use the End Process icon to send the email alert rather than the Email action item.  However, that did not work for me in this case.  I will continue to experiment, but for a 1-day alert, a 15-minute delay may be ok.  Thanks for all of your help!

You're welcome!

Hi James - I am having similar problem. I have used intermediate events like wait and send message in my process definition. They do not work. I guess it worked for you with 15 min delay. Do I need to have any scheduler in place. Let me know. Emails in my process definition only works when I put them as End message. But I need to use them as intermediate events.