Since our recent move to Lightning, we've lost the ability to use the Contact Roles feature on our Accounts. 

The given response from salesforce is to use the Account Contact Relationship object and add a checkbox called "Primary" (Primary__c)

This has been working well, but this unfortunetely doesn't prevent our sales reps from accidently selecting multiple primary contacts. 

I believe what I'm needing is a trigger on the AccountContactRelationship object that will prevent multiple people from being checked and display an error. 

I've found a few trigger codes that say they work, but all seem to error out when complied in my sandbox org as I don't believe they were written for the AccountContactRelationship object

Since our recent move to Lightning, we've lost the ability to use the Contact Roles feature on our Accounts. 

The given response from salesforce is to use the Account Contact Relationship object and add a checkbox called "Primary" (Primary__c)

This has been working well, but this unfortunetely doesn't prevent our sales reps from accidently selecting multiple primary contacts. 

I believe what I'm needing is a trigger on the AccountContactRelationship object that will prevent multiple people from being checked and display an error. 

I've found a few trigger codes that say they work, but all seem to error out when complied in my sandbox org as I don't believe they were written for the AccountContactRelationship object