Thank you Tom for sticking with me (with us so it seems). I appologize for my late responses. I cannot get the notification to work. I can reach the site but when I want to activate this function it asks me to try later. This has happened over a period of time (days).
Back to my problem.
User rights have been checked and are OK. All users have the same version of Office: Microsoft Office 365 ProPlus, november,versie 1911 (12228.20332).
I was able to track the problem ones with a debugged version of the application. The procedure works through a batch of records (recordset). For every record occurrence multiple records of other tables are updated. I was able to test it multiple times on the same recordset. Every time I ran the procedure the error popped up but the weird thing is: on different updates (tables).