Hi All

I want to update the OwnerId of a record based on a value of picklist (UCB_Status__c). 

Normally it would be easy to do with a before insert, before update trigger. But there is already a Before Insert, Before Update trigger in the system for the same object and I can not touch that trigger. 

My trigger:

trigger UCB_Coaching_Report_A_I_A_U on Coaching_Report_vod__c (after Insert, after Update)
{
      UCB_ManageCoachingReport.assignOwner(Trigger.newMap.keySet());
}

 The trigger that can not be touched: 

trigger VOD_COACHING_REPORT_BEFORE_INSUPD_TRIGGER on Coaching_Report_vod__c ( before insert, before update) {
    if(VEEVA_PROCESS_FLAGS.getUpdateCR()== true){
        System.Debug('Veeva process_Flags');
        return;
    }
    
    //UCB_ManageCoachingReport.assignOwner(Trigger.New, Trigger.oldMap);
    
   for (Integer i = 0 ; i < Trigger.new.size(); i++) 
    {
        System.Debug('In Veeva for lus');
       if (Trigger.new[i].Employee_vod__c != null ) 
         {
             System.Debug('In Veeva if employee is verschillend van 0');
             Trigger.new[i].OwnerId = Trigger.new[i].Employee_vod__c;
         }
    }   
}

The class which contains the invoked method:

public class UCB_ManageCoachingReport{   
   public static void assignManager(List<Coaching_Report_vod__c> coachingReportList){
        for(Coaching_Report_vod__c cr: coachingReportList){
            System.Debug('de user met id ' + UserInfo.getUserId() + ' wordt toegewezen aan het mananager veld');
            cr.Manager_vod__c = UserInfo.getUserId();
        }
    }

public static void assignOwner(Set<Id> crIds)
{         
       List<Coaching_Report_vod__c> crList = 
         [select Id, OwnerId, UCB_Status__c, Review_Date__c, Manager_vod__c, Employee_vod__c from Coaching_Report_vod__c where Id in:crIds];
       
          for(Coaching_Report_vod__c cr: crList )
          {               
                     if(cr.UCB_Status__c == 'Sent')
                     {
                       cr.OwnerId = cr.Employee_vod__c;
                     }
                     else
                     {
                        cr.OwnerId = cr.Manager_vod__c;
                     }     
           }
         
          update crList;      
    }
}

When I create a new Coaching Report I get the following error:

Error: Invalid Data.
Review all error messages below to correct your data.
Apex trigger UCB_Coaching_Report_A_I_A_U caused an unexpected exception, contact your administrator: UCB_Coaching_Report_A_I_A_U: execution of AfterInsert caused by: System.DmlException: Update failed. First exception on row 0 with id a1DZ0000000WFLmMAO; first error: CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY, UCB_Coaching_Report_A_I_A_U: maximum trigger depth exceeded Coaching_Report_vod trigger event AfterInsert for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm] Coaching_Report_vod trigger event AfterUpdate for [a1DZ0000000WFLm]: []: Class.UCB_ManageCoachingReport.assignOwner: line 33, column 1

I spend multiple our, changed my code 23235235253 times and still don't got a solution. 

Is it just not possible due to the trigger I can not change? 

Thanks in advance!!!