diff --git a/src/applications/project/controller/PhabricatorProjectMembersAddController.php b/src/applications/project/controller/PhabricatorProjectMembersAddController.php
index bd1631ee92..a3b89e46fd 100644
--- a/src/applications/project/controller/PhabricatorProjectMembersAddController.php
+++ b/src/applications/project/controller/PhabricatorProjectMembersAddController.php
@@ -1,72 +1,77 @@
 <?php
 
 final class PhabricatorProjectMembersAddController
   extends PhabricatorProjectController {
 
   public function handleRequest(AphrontRequest $request) {
     $viewer = $request->getViewer();
     $id = $request->getURIData('id');
 
     $project = id(new PhabricatorProjectQuery())
       ->setViewer($viewer)
       ->withIDs(array($id))
       ->requireCapabilities(
         array(
           PhabricatorPolicyCapability::CAN_VIEW,
           PhabricatorPolicyCapability::CAN_EDIT,
         ))
       ->executeOne();
     if (!$project) {
       return new Aphront404Response();
     }
 
     $this->setProject($project);
+    $done_uri = "/project/members/{$id}/";
 
     if (!$project->supportsEditMembers()) {
-      return new Aphront404Response();
-    }
+      $copy = pht('Parent projects and milestones do not support adding '.
+        'members. You can add members directly to any non-parent subproject.');
 
-    $done_uri = "/project/members/{$id}/";
+      return $this->newDialog()
+        ->setTitle(pht('Unsupported Project'))
+        ->appendParagraph($copy)
+        ->addCancelButton($done_uri);
+    }
 
     if ($request->isFormPost()) {
       $member_phids = $request->getArr('memberPHIDs');
 
       $type_member = PhabricatorProjectProjectHasMemberEdgeType::EDGECONST;
 
       $xactions = array();
 
       $xactions[] = id(new PhabricatorProjectTransaction())
         ->setTransactionType(PhabricatorTransactions::TYPE_EDGE)
         ->setMetadataValue('edge:type', $type_member)
         ->setNewValue(
           array(
             '+' => array_fuse($member_phids),
           ));
 
       $editor = id(new PhabricatorProjectTransactionEditor($project))
         ->setActor($viewer)
         ->setContentSourceFromRequest($request)
         ->setContinueOnNoEffect(true)
         ->setContinueOnMissingFields(true)
         ->applyTransactions($project, $xactions);
 
       return id(new AphrontRedirectResponse())
         ->setURI($done_uri);
     }
 
     $form = id(new AphrontFormView())
       ->setUser($viewer)
       ->appendControl(
         id(new AphrontFormTokenizerControl())
           ->setName('memberPHIDs')
           ->setLabel(pht('Members'))
           ->setDatasource(new PhabricatorPeopleDatasource()));
 
     return $this->newDialog()
       ->setTitle(pht('Add Members'))
       ->appendForm($form)
       ->addCancelButton($done_uri)
       ->addSubmitButton(pht('Add Members'));
   }
 
 }
diff --git a/src/applications/project/controller/PhabricatorProjectUpdateController.php b/src/applications/project/controller/PhabricatorProjectUpdateController.php
index 762343f485..9f8c204c55 100644
--- a/src/applications/project/controller/PhabricatorProjectUpdateController.php
+++ b/src/applications/project/controller/PhabricatorProjectUpdateController.php
@@ -1,114 +1,120 @@
 <?php
 
 final class PhabricatorProjectUpdateController
   extends PhabricatorProjectController {
 
   public function handleRequest(AphrontRequest $request) {
     $viewer = $request->getViewer();
     $id = $request->getURIData('id');
     $action = $request->getURIData('action');
 
     $capabilities = array(
       PhabricatorPolicyCapability::CAN_VIEW,
     );
 
     switch ($action) {
       case 'join':
         $capabilities[] = PhabricatorPolicyCapability::CAN_JOIN;
         break;
       case 'leave':
         break;
       default:
         return new Aphront404Response();
     }
 
     $project = id(new PhabricatorProjectQuery())
       ->setViewer($viewer)
       ->withIDs(array($id))
       ->needMembers(true)
       ->requireCapabilities($capabilities)
       ->executeOne();
     if (!$project) {
       return new Aphront404Response();
     }
 
+    $done_uri = "/project/members/{$id}/";
+
     if (!$project->supportsEditMembers()) {
-      return new Aphront404Response();
-    }
+      $copy = pht('Parent projects and milestones do not support adding '.
+        'members. You can add members directly to any non-parent subproject.');
 
-    $done_uri = "/project/members/{$id}/";
+      return $this->newDialog()
+        ->setTitle(pht('Unsupported Project'))
+        ->appendParagraph($copy)
+        ->addCancelButton($done_uri);
+    }
 
     if ($request->isFormPost()) {
       $edge_action = null;
       switch ($action) {
         case 'join':
           $edge_action = '+';
           break;
         case 'leave':
           $edge_action = '-';
           break;
       }
 
       $type_member = PhabricatorProjectProjectHasMemberEdgeType::EDGECONST;
 
       $member_spec = array(
         $edge_action => array($viewer->getPHID() => $viewer->getPHID()),
       );
 
       $xactions = array();
       $xactions[] = id(new PhabricatorProjectTransaction())
         ->setTransactionType(PhabricatorTransactions::TYPE_EDGE)
         ->setMetadataValue('edge:type', $type_member)
         ->setNewValue($member_spec);
 
       $editor = id(new PhabricatorProjectTransactionEditor($project))
         ->setActor($viewer)
         ->setContentSourceFromRequest($request)
         ->setContinueOnNoEffect(true)
         ->setContinueOnMissingFields(true)
         ->applyTransactions($project, $xactions);
 
       return id(new AphrontRedirectResponse())->setURI($done_uri);
     }
 
     $is_locked = $project->getIsMembershipLocked();
     $can_edit = PhabricatorPolicyFilter::hasCapability(
       $viewer,
       $project,
       PhabricatorPolicyCapability::CAN_EDIT);
     $can_leave = ($can_edit || !$is_locked);
 
     $button = null;
     if ($action == 'leave') {
       if ($can_leave) {
         $title = pht('Leave Project');
         $body = pht(
           'Your tremendous contributions to this project will be sorely '.
           'missed. Are you sure you want to leave?');
         $button = pht('Leave Project');
       } else {
         $title = pht('Membership Locked');
         $body = pht(
           'Membership for this project is locked. You can not leave.');
       }
     } else {
       $title = pht('Join Project');
       $body = pht(
         'Join this project? You will become a member and enjoy whatever '.
         'benefits membership may confer.');
       $button = pht('Join Project');
     }
 
     $dialog = $this->newDialog()
       ->setTitle($title)
       ->appendParagraph($body)
       ->addCancelButton($done_uri);
 
     if ($button) {
       $dialog->addSubmitButton($button);
     }
 
     return $dialog;
   }
 
 }