Error "The Expiration date needs to be entered" when creating a recurring Task (Lightning)

Question

I am trying to create a recurring task in Lightning Experience and it turns out to be difficult.

I have enabled the appropriate setting so that I am allowed to create them. I have added the "Create Recurring Series of Tasks" checkbox to the Task page layout.

I click the button "Create Follow-up Task" (which I also had to add to the page layout), because that seems to be the way to do it.

But when I want to save it, the Due Data field turns red, with the message "The Expiration date needs to be entered".

First, there is no date on which I can click. Second, data entry is prohibited in this field, the mouse cursor turns into a forbidden icon when hovering over it.

When not creating a recurring task, the Due Date field can be filled.

So: how to create a recurring task in Lightning?

Answer 1

First I saw this in Salesforce's documentation: "In Lightning Experience, the Due Date field for the series record is disabled in recurring tasks."

So that explains why the Due Date field will not let me enter any data. But then the error did not make any sense anymore. At which point it occurred to me to check for any validation rules. And that was the explanation. Someone (not me) had created this validation rule quite some time ago. I never create tasks (I am the admin, not a user), so I had never seen this validation. I was just trying to figure out how to create recurring tasks.