The scenario is I only want to validate the field upon record update not creation.It works successfully when I create or update record manually with validation rules.But it fail when I convert the Lead to Opportunity.
Created_from_Lead__c is Opportunity mapping to indicate that the Opportunity is created from Lead.But I notice there is no value map from Lead.
IF( OR(ISBLANK( TEXT(Sold_By_Business_Unit__c)),ISBLANK(Text( Sold_by_Business_Area__c )),ISBLANK(Text( Primary_Project_Group__c ))) && ISNEW() && Created_from_Lead__c, False, OR(ISBLANK( TEXT(Sold_By_Business_Unit__c)),ISBLANK(Text( Sold_by_Business_Area__c )),ISBLANK(Text( Primary_Project_Group__c ))) )
It fire an exception on after trigger below:
Error: Opportunity_Trigger: execution of AfterInsert caused by: System.DmlException: Insert failed. First exception on row 0; first error: FIELD_CUSTOM_VALIDATION_EXCEPTION, Validation rules message:  Class.Opportunity_Handler.insertOpportunityLineItem: line 274, column 1 Trigger.Opportunity_Trigger: line 43, column 1
The trigger is to insert Opportunity Line item during Opportunity creation. So I tried to remove validation rules and put the validation on the trigger itself but still it firing after trigger.
The requirement for creation or conversion it should skip validation rules.Only update will fire validation rules.
I already apply this solution on my code but still it fail.