Some of my visual workflows have been hitting permissions-related errors, and I suspect it's something to do with the Summer '16 release that hit my org over the weekend. I'm getting errors like this when end-users try to complete flows:
UPDATE --- UPDATE FAILED --- ERRORS : (INVALID_FIELD_FOR_INSERT_UPDATE) Unable to create/update fields: [CustomField__c]. Please check the security settings of this field and verify that it is read/write for your profile or permission set.
CustomField__c in this example is a field that is queried in a fast lookup element, and then later I have a fast update element to the same record - but I am not trying to have the flow change the value of that field. It never used to matter that the running user didn't have permission to edit the field. Now apparently it does?