diff --git a/module/mr/control.php b/module/mr/control.php
index d5d7603126..97e819866b 100644
--- a/module/mr/control.php
+++ b/module/mr/control.php
@@ -89,6 +89,11 @@ class mr extends control
         }
 
         $MR = $this->mr->getByID($MRID);
+        if(isset($MR->gitlabID)) $rawMR = $this->mr->apiGetSingleMR($MR->gitlabID, $MR->targetProject, $MR->mriid);
+        $this->view->title = $this->lang->mr->edit;
+        $this->view->MR    = $MR;
+        $this->view->rawMR = isset($rawMR) ? $rawMR : false;
+        if(!isset($rawMR->id) or (isset($rawMR->message) and $rawMR->message == '404 Not found') or empty($rawMR)) return $this->display();
 
         $branchList       = $this->loadModel('gitlab')->getBranches($MR->gitlabID, $MR->targetProject);
         $targetBranchList = array();
@@ -167,12 +172,12 @@ class mr extends control
     {
         $MR = $this->mr->getByID($id);
         if(isset($MR->gitlabID)) $rawMR = $this->mr->apiGetSingleMR($MR->gitlabID, $MR->targetProject, $MR->mriid);
-        $MR = $this->mr->apiSyncMR($MR); /* Sync MR from GitLab to ZentaoPMS. */
-
         $this->view->title = $this->lang->mr->view;
         $this->view->MR    = $MR;
         $this->view->rawMR = isset($rawMR) ? $rawMR : false;
+        if(!isset($rawMR->id) or (isset($rawMR->message) and $rawMR->message == '404 Not found') or empty($rawMR)) return $this->display();
 
+        $MR = $this->mr->apiSyncMR($MR); /* Sync MR from GitLab to ZentaoPMS. */
         $this->loadModel('gitlab');
         $sourceProject = $this->gitlab->apiGetSingleProject($MR->gitlabID, $MR->sourceProject);
         $targetProject = $this->gitlab->apiGetSingleProject($MR->gitlabID, $MR->targetProject);
@@ -273,7 +278,12 @@ class mr extends control
         $encoding = empty($encoding) ? 'utf-8' : $encoding;
         $encoding = strtolower(str_replace('_', '-', $encoding)); /* Revert $config->requestFix in $encoding. */
 
-        $MR      = $this->mr->getByID($MRID);
+        $MR = $this->mr->getByID($MRID);
+        if(isset($MR->gitlabID)) $rawMR = $this->mr->apiGetSingleMR($MR->gitlabID, $MR->targetProject, $MR->mriid);
+        $this->view->title = $this->lang->mr->viewDiff;
+        $this->view->rawMR = $rawMR;
+        if(!isset($rawMR->id) or (isset($rawMR->message) and $rawMR->message == '404 Not found') or empty($rawMR)) return $this->display();
+
         $diffs   = $this->mr->getDiffs($MR, $encoding = '');
         $arrange = $this->cookie->arrange ? $this->cookie->arrange : 'inline';
 
@@ -309,7 +319,6 @@ class mr extends control
 
         $this->view->repo     = $this->loadModel('repo')->getRepoByID($MR->repoID);
         $this->view->repoID   = $MR->repoID;
-        $this->view->title    = $this->lang->mr->viewDiff;
         $this->view->diffs    = $diffs;
         $this->view->encoding = $encoding;
         $this->view->arrange  = $arrange;
@@ -388,6 +397,9 @@ class mr extends control
      */
     public function addBug($repoID, $file, $v1, $v2)
     {
+        /* Handle the exception that when $repoID is empty. */
+        if($repoID == "0") $this->send(array());
+
         $this->loadModel('repo');
         if($this->get->repoPath) $file = $this->get->repoPath;
         if(!empty($_POST))
@@ -397,7 +409,10 @@ class mr extends control
 
             $bugID    = $result['id'];
             $repo     = $this->repo->getRepoById($repoID);
-            $entry    = $repo->name . '/' . $this->repo->decodePath($file);
+            /* Handle the exception that when $repo is empty. */
+            if(empty($repo)) $this->send(array());
+
+            $entry    = isset($repo->name) ? $repo->name . '/' . $this->repo->decodePath($file) : '';
             $location = sprintf($this->lang->repo->reviewLocation, $entry, $repo->SCM != 'Subversion' ? substr($v2, 0, 10) : $v2, $this->post->begin, $this->post->end);
             if(empty($v1))
             {
diff --git a/module/mr/view/diff.html.php b/module/mr/view/diff.html.php
index 406aff76e7..d7d91ab097 100644
--- a/module/mr/view/diff.html.php
+++ b/module/mr/view/diff.html.php
@@ -11,6 +11,18 @@
 <?php include '../../common/view/header.html.php';?>
 <?php include '../../common/view/form.html.php';?>
 <?php include '../../common/view/kindeditor.html.php';?>
+<!-- If this mr is deleted in GitLab, then show this part to user. -->
+<?php if(empty($rawMR) or !isset($rawMR->id)): ?>
+  <div id='mainContent'>
+    <div class="table-empty-tip">
+      <p>
+        <span class="text-muted"><?php echo $lang->mr->notFound; ?></span>
+        <?php echo html::a($this->createLink('mr', 'browse'), "<i class='icon icon-plus'></i> " . $lang->mr->browse, '', "class='btn btn-info'"); ?>
+      </p>
+    </div>
+  </div>
+<?php die; endif;?>
+
 <?php include 'header.review.html.php';?>
 <?php if(!isonlybody()):?>
 <div id='mainMenu' class='clearfix'>
diff --git a/module/mr/view/edit.html.php b/module/mr/view/edit.html.php
index 1855f7fadb..493438235e 100644
--- a/module/mr/view/edit.html.php
+++ b/module/mr/view/edit.html.php
@@ -11,6 +11,18 @@
 <?php include '../../common/view/header.html.php';?>
 <?php js::set('gitlabID', $MR->gitlabID);?>
 <?php js::set('projectID', $MR->sourceProject);?>
+<!-- If this mr is deleted in GitLab, then show this part to user. -->
+<?php if(empty($rawMR) or !isset($rawMR->id)): ?>
+  <div id='mainContent'>
+    <div class="table-empty-tip">
+      <p>
+        <span class="text-muted"><?php echo $lang->mr->notFound; ?></span>
+        <?php echo html::a($this->createLink('mr', 'browse'), "<i class='icon icon-plus'></i> " . $lang->mr->browse, '', "class='btn btn-info'"); ?>
+      </p>
+    </div>
+  </div>
+<?php die; endif;?>
+
 <div id='mainContent' class='main-row'>
   <div class='main-col main-content'>
     <div class='center-block'>
diff --git a/module/mr/view/header.review.html.php b/module/mr/view/header.review.html.php
index 6aba0f3430..326a5ae803 100644
--- a/module/mr/view/header.review.html.php
+++ b/module/mr/view/header.review.html.php
@@ -6,7 +6,7 @@ $lastReview  = $this->mr->getLastReviewInfo($file);
 $repoModule  = isset($lastReview) && isset($lastReview->module) ? $lastReview->module : '';
 
 /* Get product pairs. */
-if($repo->product)
+if(isset($repo->product) and $repo->product)
 {
     $products = $this->dao->select('id,name')->from(TABLE_PRODUCT)->where('`id`')->in($repo->product)->fetchPairs();
 }
diff --git a/module/mr/view/view.html.php b/module/mr/view/view.html.php
index 5a43805908..38f66b4021 100644
--- a/module/mr/view/view.html.php
+++ b/module/mr/view/view.html.php
@@ -1,16 +1,26 @@
 <?php include '../../common/view/header.html.php'; ?>
-<?php if (!isset($MR->id)) : ?>
+<?php if(!isset($MR->id)): ?>
   <div id='mainContent'>
     <div class="table-empty-tip">
       <p>
         <span class="text-muted"><?php echo $lang->mr->notFound; ?></span>
-        <?php if (common::hasPriv('mr', 'create')) : ?>
+        <?php if(common::hasPriv('mr', 'create')): ?>
           <?php echo html::a($this->createLink('mr', 'create'), "<i class='icon icon-plus'></i> " . $lang->mr->create, '', "class='btn btn-info'"); ?>
         <?php endif; ?>
       </p>
     </div>
   </div>
-<?php else : ?>
+<!-- If this mr is deleted in GitLab, then show this part to user. -->
+<?php elseif(empty($rawMR) or !isset($rawMR->id)): ?>
+  <div id='mainContent'>
+    <div class="table-empty-tip">
+      <p>
+        <span class="text-muted"><?php echo $lang->mr->notFound; ?></span>
+        <?php echo html::a($this->createLink('mr', 'browse'), "<i class='icon icon-plus'></i> " . $lang->mr->browse, '', "class='btn btn-info'"); ?>
+      </p>
+    </div>
+  </div>
+<?php else: ?>
   <div class="btn-toolbar pull-left">
     <?php echo html::a($this->createLink('mr', 'browse'), '<i class="icon icon-back icon-sm"></i> ' . $lang->goback, '', "class='btn btn-secondary'"); ?>
     <div class="divider"></div>