We are planning to convert an existing Master-Detail relationship to lookup relations. I wanted to know if there will be loss of existing association when the field type is changed from M-D to lookup.

I know when Converting Relationships

You can convert a master-detail relationship to a lookup relationship as long as no roll-up summary fields exist on the master object.

but unsure about data loss.

2 Answers 2


I had done a quick check and did not found any issue in data loss. All the values of the record has been retained even the relationship field value except rollup summaries field value. Anyways, System will not allows you to change the data type when you have it.

What would worry you is all the reports you had earlier and re work on org wide settings and sharing rule.

  • Reports will have to be rebuilt is perhaps the most annoying problem.
    – sfdcfox
    Apr 22, 2020 at 11:48
  • Thanks, Sanket, Narey and sfdcfox for getting back on this. Apr 22, 2020 at 16:38

if A is master of B then if you need to change this master detail relationship to lookup then you only need to click on setup ->

obeject;> master detail field > Edit> now you will not be able to see button "change field type" if there is Roll up summary field on Master objetc so delete it first and also remove it from "deleted fied" trash box then you will be able to see"change field type" button.

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