Policy update Java exception

[Former Community Member]

I'm getting this exception when trying update a Policy.

                //Get ServiceClientFactory
          ServiceClientFactory myFactory = getServiceClientFactory();
               
          // Create an RightsManagementClient object
          RightsManagementClient rightsClient = new RightsManagementClient(myFactory);
          
          // Create an DirectoryManager object
          DirectoryManager dirManager = new DirectoryManagerServiceClient(myFactory);
               
          
          //Create a policy manager instance
             PolicyManager policyManager = rightsClient.getPolicyManager();
        
             //Retrieve an existing policy
             Policy myPolicy = policyManager.getPolicy(da.getProduct().getPolicySet(),da.getProduct().getPolicyName());
            
            
             //     Grab the Principal (aka User)
             Principal p = retrievePrincipal(da.getCustomer().getEmail(), dirManager);
            
            
             logger.info("Policy grabbed");
            
             List<PolicyEntryImpl> policyEntries = myPolicy.getPolicyEntries();
     
             for(PolicyEntryImpl pe : policyEntries){
                  
                  Principal pep = pe.getPrincipal();
                  if(p.getOid().equals(pep.getCanonicalName())){
                       myPolicy.removePolicyEntry(pe);
                       logger.info("Policy removed");
                  }
                  
                  
             }
            
            
             //Update the policy
             policyManager.updatePolicy(myPolicy);