I am writing some code that will automatically convert leads in certain situations. Additionally, the code searches for contacts with the same email address, and associates the converted lead with the existing Contact and the Contact's related Account. If there is no matching Contact, it searches for an Account where a custom field called Domain__c matches the value of Domain__c on the Lead being converted. If that's found, the Lead is converted to a new Contact on an existing Account. Otherwise, it creates a new Contact and Account.

Here is the error I am receiving. So far, Salesforce support has not been helpful in pointing me in the right direction.

Error:Apex trigger leadTrigger caused an unexpected exception, contact your administrator: leadTrigger: execution of AfterUpdate caused by: System.DmlException: ConvertLead failed. First exception on row 0; first error: UNKNOWN_EXCEPTION, An unexpected error occurred. Please include this ErrorId if you contact support: 711698393-71813 (759071441): []: Class.LeadConverter.convertLead: line 143, column 1

I wrote this as a static method for now, but I'll be updating to make the code more generic to handle multiple different cases once I get this version working. Here's my trigger:

trigger leadTrigger on Lead (before insert, before update, after insert, after update) {
    //before insert 
    if(Trigger.isBefore && Trigger.isInsert){
        
    } 
    //before update 
    if(Trigger.isBefore && Trigger.isUpdate){
        
    }
    //after insert
    if(Trigger.isAfter && Trigger.isInsert){
        LeadConverter.convertLead(Trigger.new);
    }
    //after update
    if(Trigger.isAfter && Trigger.isUpdate){ 
        LeadConverter.convertLead(Trigger.new);
    }
}

And here is my Class:

public class LeadConverter {

	public static void convertLead(List<Lead> leads){
		Set<String> domains = new Set<String>();
		Set<String> emailAddresses = new Set<String>();
		List<Lead> leadsToConvert = new List<Lead>();
		List<Database.LeadConvert> leadConverts = new List<Database.LeadConvert>();
		
		LeadStatus convertStatus = [SELECT MasterLabel FROM LeadStatus WHERE IsConverted = true LIMIT 1];
		
		for (Lead l: leads){
			if(l.LeadSource == 'SSL Distro' && l.Domain__c != null
			 && l.Email != null && !l.isConverted){
				if(l.Domain__c != null){ domains.add(l.Domain__C); }
				if(l.Email != null){ emailAddresses.add(l.Email); }
				leadsToConvert.add(l);
			}//end if statement on Lead Source	
		}//end leads for loop
        
        List<Account> exstingAccounts = [SELECT Id, Name, Domain__c FROM Account WHERE Domain__c IN :domains];
        List<Contact> exstingContacts = [SELECT Id, AccountID, FirstName, LastName, Email, Email_ID__c 
        								FROM Contact WHERE Email_ID__c IN : emailAddresses];
        								
        Map<String, Contact> emailContactIdMap = new Map<String, Contact>();	
        Map<String, Account> domainAccountIdMap = new Map<String, Account>();	
        	
        for (Contact c: exstingContacts){ emailContactIdMap.put(c.Email_ID__c, c); }						
		for (Account a: exstingAccounts){ domainAccountIdMap.put(a.Domain__c, a); }
		
		for (Lead l: leadsToConvert){
			Database.LeadConvert lc = new Database.LeadConvert();
			if (emailContactIdMap.get(l.Email) != null && !l.isConverted){
				if(emailContactIdMap.get(l.Email).AccountId != null){
					lc.setContactId(emailContactIdMap.get(l.Email).Id);
					lc.setAccountId(emailContactIdMap.get(l.Email).AccountId);
				}	
			} else if (domainAccountIdMap.get(l.Domain__c) != null && !l.isConverted){
				lc.setAccountId(domainAccountIdMap.get(l.Domain__c).Id);
			}
			lc.setLeadId(l.Id);
			lc.setDoNotCreateOpportunity(true);
			lc.setConvertedStatus(convertStatus.MasterLabel); 
			
			leadConverts.add(lc);
		}//end leads to convert for loop
		
		System.debug('The list of items to convert has a size of: ' + leadConverts.size() );
		
			if(!leadConverts.isEmpty()){
				List<Database.LeadConvertResult> lcr = Database.convertLead(leadConverts);
			}
		
	}
}