Master-Detail: Field is not writable error on Apex

I came upon this error when I am assigning the custom object to the master standard object.

Eg. accountId derived from a query

Then I get this error.

The fix was actually easy. I just rewrote it to assign the master id on instantiating the child object.

Hope somebody finds this useful.

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6 thoughts on “Master-Detail: Field is not writable error on Apex

    1. The example is for an insert DML. For update operation as the child record already exists, updating the record relationship should work fine as is.

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