I have the following objects Training_Group_Criteria__c and Training_Group_Rule__c. I am trying to create a master-detail field to make Training_Group_Rule__c a detail of Training_Group_Criteria__c. But when I come to the drop down of objects which can be a master I do not find Training_Group_Criteria__c. What may I try and why is that even possible?

Thank you.

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  • Do you have any data in Training_Group_Rule__c?
    – Jayant Das
    Dec 4 '18 at 17:06
  • @JayantDas, what do you mean by data in object? Dec 4 '18 at 17:07
  • Take a look at this link, if that's your case.
    – Jayant Das
    Dec 4 '18 at 17:07
  • @JayantDas, ok let me delete all the records which are of type to which I want to add a master-detail relationship and get back to you. Dec 4 '18 at 17:08
  • Do you already have a lookup relationship to that object and you are trying to change it to M-D?
    – Jayant Das
    Dec 4 '18 at 17:09

If you already have a lookup relationship to an object, and that you don't have values populated on that field for records, then you cannot change the field to be a Master-Detail relationship.

Refer to the help documentation

You can convert a lookup relationship to a master-detail relationship, but only if the lookup field in all records contains a value.

and this knowledge article for details.

Salesforce will not accommodate a master detail relationship to a custom object that already contains data.

This is because creating a master detail relationship adds a new required field to the custom object (known as a "foreign key" to database administrators). Each data record in the object needs to have a valid value in the field -- it cannot be left blank.

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