You have setup workflow to assign tasks to users and notify users in your system. But your workflow fails to notify users with the error below:
Suspend this workflow
Activity in progress
Retrying last request. Next attempt scheduled after 9/13/2016 12:08 PM. Details of last request: HTTP Unauthorized to https://xyz.sharepoint.com/sites/_api/sp.utilities.utility.SendEmail Correlation Id: 04c60d70-3e20-fd47-8eff-4de263aa5958 Instance Id: fc66dfa5-7fcb-4548-a289-6b5d9b774719
Access denied. You do not have permission to perform this action or access this resource.
So, the issue stems from permission obviously. In my case I had a requirement where in user should ONLY be able to submit to master list, workflow tasks and history but NOT be able to update the site.
Site > Owners – full control, Members – Edit and Viewers – Restricted read
Master Lists, Workflow Tasks and Workflow History > Contribute
I had setup item level permission removing contribute access for item for the entire AD group and giving only the author of the item contribute access as seen in pic below:
I have also changed the master page security for viewlsts.aspx from ViewFormPages to ManageWeb so I can hide site contents from all staff except admins.
Then my workflow suddenly stops notifying users. It assign tasks with no issues, it simply refused to email users and kept throwing this error in workflow status
Upon checking everything in the list and ruling out permission on that front, I noticed the ‘restricted read’ permission for viewers in the site. Changing that to View Only did the trick for me.
This is the group that had All Staff AD Group who had to submit the form. Once that group was giving ‘View Only’, emails started to flow through along with task assignments, whenever a staff submitted a request.
If it were a SharePoint Group, then View Membership setting changed to ‘Everyone’ should resolve the issue.