
Cannot Create Master-Detail Relationship
You cannot create a new Master-Detail relationship on an existing custom object if records already exist. You must first create a Lookup relationship, populate the lookup field with data in all records, and then change the relationship type to Master-Detail.
Anyway, I have an absolutely new object with no records at all and I DO trying to create a lookup relationship. Did somebody experience this problem already?
Thanks a lot!
Olga
8 answers

Ok, I found the answer. You create a lookup to Product-Object only if you allow to clear the field if the Product is deleted:
Error: Invalid Data.
Review all error messages below to correct your data.
Cannot add a lookup relationship child with cascade or restrict options to Product2
The initial error message is misleading.