Hi Guys,

We have a trigger on Lead Conversion which checks for some fields (if htey are blank) and display a error message in Convert Popup(in Lightining). That is working fine. But the only issue is the new line is not working in the UI.

Here is my trigger : I have added a new line every time I append the error string. but it doesn't show up in the conversion popup in Lightning. 

trigger MandatoryFieldsLeadConversion on Lead (before Update) 
{

           // Select Id,ParentAccount__c,FirstName,Email,Phone,Company,Country__c,Industry_Ipay__c,Trading_Name__c,Street,State,City,PostalCode,Sales_Channel__c,Avg_Trans_Amount__c,Trans_Per_Month__c,Max_Single_Pay_Amt__c,Director_1_First_Name__c,Director_1_Last_Name__c,Director_Email__c,Direct_Debit_Requested__c,eCommerce__c,Video_Payment__c,Xero_Payment_Now__c,Xero_Direct_Debit__c
        
        String sBreak = '<br/>';    
        Boolean hasError = false;
        for (Lead l : Trigger.new)
         {
            if (Trigger.oldMap.get(l.id).isConverted == false && Trigger.newMap.get(l.id).isConverted == true) // to check only in Lead Coversion
             {  
                 String erstring = 'Please Enter Below Mandatory Fields before converting this Lead \n';
               //Lead l = [Select Id,ParentAccount__c,FirstName,Email,Phone,Company,Country__c,Industry_Ipay__c,Trading_Name__c,Street,State,City,PostalCode,Sales_Channel__c,Avg_Trans_Amount__c,Trans_Per_Month__c,Max_Single_Pay_Amt__c,Director_1_First_Name__c,Director_1_Last_Name__c,Director_Email__c,Direct_Debit_Requested__c,eCommerce__c,Video_Payment__c,Xero_Payment_Now__c,Xero_Direct_Debit__c From Lead Where Id in  :trigger.new[i]];
                 //Skip this check for V3 and IODM Leads
               if((l.ParentAccount__c != '0019000001YHuxWAAT') && (l.ParentAccount__c != '0016F00001i2yYHQAY'))
                 { 
                     //if Parent Account is Blank
                   if((l.ParentAccount__c == null) || (l.ParentAccount__r.Name ==  ' '))
                   { 
                    erstring += '\n Parent Account' ; 
                    hasError = true; 
                   }
                     //if First Name is Blank
                   if((l.FirstName == null) || (l.FirstName ==  ' '))
                   {
                     erstring += '\nFirst Name'  ;
                     hasError = true; 
                   }
                     //if Email is Blank
                   if((l.Email == null) || (l.Email ==  ' '))
                   {
                     erstring += '\n Email';
                     hasError = true; 
                   }
                      //if Phone is Blank
                   if((l.Phone == null) || (l.Phone ==  ' '))
                   {
                     erstring += '\nPhone                          ';
                     hasError = true; 
                   }
                      //if Company is Blank
                   if((l.Company == null) || (l.Company ==  ' '))
                   {
                     erstring += 'Company \n';
                     hasError = true; 
                   }
                      //if Country is Blank
                   if((l.Country__c == null) || (l.Country__c ==  ' '))
                   {
                     erstring += 'Country \n';
                     hasError = true; 
                   } 
                      //if Industry is Blank
                   if((l.Industry_Ipay__c == null) || (l.Industry_Ipay__r.Name ==  ' '))
                   {
                     erstring += 'Industry \n';
                     hasError = true; 
                   }  
                      //if Parent Account is Blank
                   if((l.Trading_Name__c == null) || (l.Trading_Name__c ==  ' '))
                   {
                     erstring += 'Trading Name \n';
                     hasError = true; 
                   }
                      //if Address is Blank
                   if((l.Street == null) || (l.Street ==  ' '))
                   {
                     erstring += 'Street \n';
                     hasError = true; 
                   }
                    if((l.State == null) || (l.State ==  ' '))
                   {
                     erstring += 'State \n';
                     hasError = true; 
                   }
                   if((l.City == null) || (l.City ==  ' '))
                   {
                     erstring += 'City \n';
                     hasError = true; 
                   }   
                   if((l.PostalCode == null) || (l.PostalCode ==  ' '))
                   {
                     erstring += 'Post Code \n';
                     hasError = true; 
                   } 
                      //if Sales channel is Blank
                   if((l.Sales_Channel__c == null) || (l.Sales_Channel__c ==  ' '))
                   {
                     erstring += 'Sales Channel \n';
                     hasError = true; 
                   } 
                      //if Average Transaction Amount is Blank
                   if((l.Avg_Trans_Amount__c == null) || (l.Sales_Channel__c ==  ' '))
                   {
                     erstring += 'Average Transaction Amount \n';
                     hasError = true; 
                   } 
                      //ifTransactions per month is Blank
                   if((l.Trans_Per_Month__c == null) )
                   {
                     erstring += 'Transactions per month \n';
                     hasError = true; 
                   }
                      //if Max Singl ePay Amount is Blank
                   if((l.Max_Single_Pay_Amt__c == null))
                   {
                     erstring += 'Maximum single payment amount \n';
                     hasError = true; 
                   }
                      //ifDirector Details Blank
                   if((l.Director_1_First_Name__c == null) || (l.Director_1_First_Name__c ==  ' '))
                   {
                     erstring += 'Director First Name  \n';
                     hasError = true; 
                   } 
                   if((l.Director_1_Last_Name__c == null) || (l.Director_1_Last_Name__c ==  ' '))
                   {
                     erstring += 'Director Last Name  \n';
                     hasError = true; 
                   } 
                   if((l.Director_Email__c == null) || (l.Director_Email__c ==  ' '))
                   {
                     erstring += 'Director Last Name  \n';
                     hasError = true; 
                   } 
                      //if no products selected 
                   if(!((l.Direct_Debit_Requested__c) || (l.eCommerce__c) || (l.Video_Payment__c) || (l.Xero_Payment_Now__c) || (l.Xero_Direct_Debit__c) ))
                   {
                     erstring += 'One of the products Direct Debit Requested/Ecommerce/Video Payment/Xero Payment Now/Xero Direct Debit is not selected';
                     hasError = true; 
                   } 
                      //Finally add the error message if any of the fields above atre blank
                   if(hasError)
                   {
                     l.addError( erstring,false);
                   }
                  }
             }  
         }
}

Attached the popup screenshot. Does any one have any idea what is wrong?