Sorry, for some reason, my reply was cut down. Here is the complete reply.
Hello,
Thanks for these screenshots, it is clearer in english.
This being said, your automation is not clear to me.
First point, trigger and all 2 actions are set on the same table "Fahrzeugliste".
Second point, you have a "Find records" action, but you do not seem to use the result of this action.
From my understanding, your automation tries do do the following:
-1- If status becomes "Erledigt" for a record from table "Fahrzeugliste" then
-2- Update this record by passing "Datum der HU/AU..." value to field "Letzer HU/AU Termin"
Hence, unless I am missing something, your "Find records" action is not being used.
But it does not explain why you automation fails. I see that the field "Datum der HU/AU..." used to update field "Letzer HU/AU Termin" is a lookup field. If your linked field to table "vehicle list" allows multiple values to be linked with, then you may have more than one date in the lookup field explaining why the automation fails.
Here is the error message that I get when I link a record from table Fahrzeugliste to more than one record on table "vehicle list":
It works fine when I make sure that it is linked to just one record.
Regards,
Pascal