$m = new ModelName;

$m->name = 'Test model insert';
$m->save();

$m1 = ModelName::find( $m->id );

if ($m1) {
  $m1->name = 'Test model update';
  $m1->save();  // Error occured here.
}

trait WithoutUpdateId
{
   /**
    * Perform a model update operation.
    *
    * @param  IlluminateDatabaseEloquentBuilder $query
    *
    * @return bool
    */
   protected function performUpdate(Builder $query)
   {
       // If the updating event returns false, we will cancel the update operation so
       // developers can hook Validation systems into their models and cancel this
       // operation if the model does not pass validation. Otherwise, we update.
       if ($this->fireModelEvent('updating') === false) {
           return false;
       }

       // First we need to create a fresh query instance and touch the creation and
       // update timestamp on the model which are maintained by us for developer
       // convenience. Then we will just continue saving the model instances.
       if ($this->usesTimestamps()) {
           $this->updateTimestamps();
       }

       // Once we have run the update operation, we will fire the "updated" event for
       // this model instance. This will allow developers to hook into these after
       // models are updated, giving them a chance to do any special processing.
       $dirty = $this->getDirty();

       if (count($dirty) > 0) {
           unset($dirty['id']);
           $this->setKeysForSaveQuery($query)->update($dirty);

           $this->fireModelEvent('updated', false);

           $this->syncChanges();
       }

       return true;
   }

class ModelName extends Model
{
  use WithoutUpdateId;
   ...
}