You can add an error to a specific field using the addError method as follows:

SObject someRecord;
someRecord.SomeField__c.addError('Custom Message');
//or
someRecord.someField__c.addError(someException);

Note that you cannot add it to a field dynamically. This error mapping can only be done with a hard-coded field. See also:

• Provide an additional addError method on SObject that accepts a field name
• How to use addError() with a dynamically derived field name?

You can add an error to a specific field using the addError method as follows:

SObject someRecord;
someRecord.SomeField__c.addError('Custom Message');
//or
someRecord.someField__c.addError(someException);

Note that you cannot add it to a field dynamically. This error mapping can only be done with a hard-coded field. See also:

• Provide an additional addError method on SObject that accepts a field name
• How to use addError() with a dynamically derived field name?