Formatting issue when using group by

[Berl21]

Hi,

I need to use the feature group by for one of my project. Usually there are no issues but there is an error message in this case. I can't infer what it means and which column is the problem.

Here are the screenshots for the grouping step and its results. How can I solve this?

Thanks for any help regarding this!

Pauline. 

[HotChilli · Accepted solution]

I don't think it's a 'Group By ' problem, it has just been exposed by the Group By.

There are text characters in a field (probably AnfrageNummer) which has a number type.

Test it by changing all the number fields (try AnfrageNummer first) to text before doing the Group By