On the OpportunityLineItem I have two triggers: One that updates the Unit Price and another that applies a Discount before the record is Saved and another that Updates a field on the Opportunity. Both work fine separately but when put together the insert after creates a problem where I get the following error message:

OpportunityLineItemTrigger: execution of AfterInsert caused by: System.FinalException: Record is read-only Trigger.OpportunityLineItemTrigger: line 12, column 1
 

trigger OpportunityLineItemTrigger on OpportunityLineItem (before insert, before update, after update, after insert) {
    List<Opportunity> opps = new List<Opportunity>();
    List<Id> oppIds = new List<Id>();
    Decimal contractLengthMonths = 0;

//---------------BEFORE TRIGGER BELOW----------
    if(trigger.isInsert || trigger.isUpdate && trigger.isBefore) {
        List<OpportunityLineItem> oli = new List<OpportunityLineItem>();
        for (OpportunityLineItem oli2: trigger.new){
            if(oli2.Number_of_Months__c > 0){
                oli2.UnitPrice = ((oli2.Number_of_Months__c / 12) * oli2.Unit_Price2__c);
            } else if (oli2.Number_of_Months__c == null || oli2.Number_of_Months__c == 0 ) {
                oli2.UnitPrice = oli2.Unit_Price2__c;
            }
            if(oli2.Adjusted_Gross_Margin_Percentage__c == 0 && oli2.Product_Gross_Margin_Percent2__c != 0 ) {
                if (oli2.Number_of_Months__c > 0) {
                    oli2.Gross_Margin_Dollars__c = (oli2.Unit_Price2__c * oli2.Quantity * (oli2.Number_of_Months__c / 12)) * (oli2.Product_Gross_Margin_Percent2__c/100);
                } else {
                    oli2.Gross_Margin_Dollars__c = (oli2.Unit_Price2__c * oli2.Quantity) * (oli2.Product_Gross_Margin_Percent2__c/100);
                }
             } else if (oli2.Adjusted_Gross_Margin_Percentage__c > 0) {
                if (oli2.Number_of_Months__c > 0) {
                    oli2.Gross_Margin_Dollars__c = (oli2.Unit_Price2__c * oli2.Quantity * (oli2.Number_of_Months__c / 12)) * (oli2.Adjusted_Gross_Margin_Percentage__c/100);
                } else {
                    oli2.Gross_Margin_Dollars__c = (oli2.Unit_Price2__c * oli2.Quantity) * (oli2.Adjusted_Gross_Margin_Percentage__c/100);
                }
            }//END if(oli2.Adjusted_Gross_Margin_Percentage__c == 0 || oli2.Adjusted_Gross_Margin_Percentage__c == null) 
            
        }//END for (OpportunityLineItem oli2: trigger.new)
    }//if(trigger.isInsert || trigger.isUpdate && trigger.isBefore) 

//---------AFTER TRIGGER BELOW--------------

    if(trigger.isAfter) {
        for (OpportunityLineItem oli3: trigger.new){
            oppids.add(oli3.opportunityId);
            
        }//END for (OpportunityLineItem oli3: trigger.new)
        List<OpportunityLineItem> allOLI = [SELECT id, Number_of_Months__c FROM OpportunityLineItem WHERE OpportunityId in: oppids];
        List<Opportunity> oppsToUpdate = [SELECT id, Contract_Length_Months__c FROM Opportunity WHERE id in: oppids];
        if(allOLI.size() > 0){
            for(OpportunityLineItem allOLI2: allOLI){
                if(allOLI2.Number_of_Months__c > contractLengthMonths){
                    contractLengthMonths = allOLI2.Number_of_Months__c;
                } else if (allOLI2.Number_of_Months__c == null) {
                    contractLengthMonths = 12;
                }
            } //END for(OpportunityLineItem allOLI2: allOLI)
            for(Opportunity oppUpdate: oppsToUpdate){
                oppUpdate.Contract_Length_Months__c = contractLengthMonths;
                opps.add(oppUpdate);
            }// END for(Opportunity oppUpdate: oppsToUpdate)
 
        }//END if(allOLI.size() > 0
        update opps;
    }//if(trigger.isAfter)
}//END OpportunityLineItem Class

Your help would be greatly appreciated.

Robert​