diff --git a/CRM/Contact/Form/Merge.php b/CRM/Contact/Form/Merge.php
index 9445834f0a7c..a026f35d328d 100644
--- a/CRM/Contact/Form/Merge.php
+++ b/CRM/Contact/Form/Merge.php
@@ -64,171 +64,166 @@ class CRM_Contact_Form_Merge extends CRM_Core_Form {
   var $_qfZeroBug = 'e8cddb72-a257-11dc-b9cc-0016d3330ee9';
 
   public function preProcess() {
-    if (!CRM_Core_Permission::check('merge duplicate contacts')) {
-      CRM_Core_Error::fatal(ts('You do not have access to this page'));
-    }
-
-    $cid = CRM_Utils_Request::retrieve('cid', 'Positive', $this, TRUE);
-    $oid = CRM_Utils_Request::retrieve('oid', 'Positive', $this, TRUE);
-    $flip = CRM_Utils_Request::retrieve('flip', 'Positive', $this, FALSE);
-
-    $this->_rgid = CRM_Utils_Request::retrieve('rgid', 'Positive', $this, FALSE);
-    $this->_gid = $gid = CRM_Utils_Request::retrieve('gid', 'Positive', $this, FALSE);
-    $this->_mergeId = CRM_Utils_Request::retrieve('mergeId', 'Positive', $this, FALSE);
-    $this->limit = CRM_Utils_Request::retrieve('limit', 'Positive', $this, FALSE);
-    $urlParams = "reset=1&rgid={$this->_rgid}&gid={$this->_gid}&limit=" . $this->limit;
+    try {
 
-    $this->bounceIfInvalid($cid, $oid);
+      $this->_cid = CRM_Utils_Request::retrieve('cid', 'Positive', $this, TRUE);
+      $this->_oid = CRM_Utils_Request::retrieve('oid', 'Positive', $this, TRUE);
+      $flip = CRM_Utils_Request::retrieve('flip', 'Positive', $this, FALSE);
 
-    $this->_contactType = civicrm_api3('Contact', 'getvalue', array('id' => $cid, 'return' => 'contact_type'));
+      $this->_rgid = CRM_Utils_Request::retrieve('rgid', 'Positive', $this, FALSE);
+      $this->_gid = $gid = CRM_Utils_Request::retrieve('gid', 'Positive', $this, FALSE);
+      $this->_mergeId = CRM_Utils_Request::retrieve('mergeId', 'Positive', $this, FALSE);
+      $this->limit = CRM_Utils_Request::retrieve('limit', 'Positive', $this, FALSE);
+      $urlParams = "reset=1&rgid={$this->_rgid}&gid={$this->_gid}&limit=" . $this->limit;
 
-    $browseUrl = CRM_Utils_System::url('civicrm/contact/dedupefind', $urlParams . '&action=browse');
+      $this->bounceIfInvalid($this->_cid, $this->_oid);
 
-    if (!$this->_rgid) {
-      // Unset browse URL as we have come from the search screen.
-      $browseUrl = '';
-      $this->_rgid = civicrm_api3('RuleGroup', 'getvalue', array(
-        'contact_type' => $this->_contactType,
-        'used' => 'Supervised',
-        'return' => 'id',
+      $this->_contactType = civicrm_api3('Contact', 'getvalue', array(
+        'id' => $this->_cid,
+        'return' => 'contact_type',
       ));
-    }
-    $this->assign('browseUrl', $browseUrl);
-    if ($browseUrl) {
-      CRM_Core_Session::singleton()->pushUserContext($browseUrl);
-    }
 
-    $cacheKey = CRM_Dedupe_Merger::getMergeCacheKeyString($this->_rgid, $gid);
+      $browseUrl = CRM_Utils_System::url('civicrm/contact/dedupefind', $urlParams . '&action=browse');
 
-    $join = CRM_Dedupe_Merger::getJoinOnDedupeTable();
-    $where = "de.id IS NULL";
+      if (!$this->_rgid) {
+        // Unset browse URL as we have come from the search screen.
+        $browseUrl = '';
+        $this->_rgid = civicrm_api3('RuleGroup', 'getvalue', array(
+          'contact_type' => $this->_contactType,
+          'used' => 'Supervised',
+          'return' => 'id',
+        ));
+      }
+      $this->assign('browseUrl', $browseUrl);
+      if ($browseUrl) {
+        CRM_Core_Session::singleton()->pushUserContext($browseUrl);
+      }
 
-    $pos = CRM_Core_BAO_PrevNextCache::getPositions($cacheKey, $cid, $oid, $this->_mergeId, $join, $where, $flip);
+      $cacheKey = CRM_Dedupe_Merger::getMergeCacheKeyString($this->_rgid, $gid);
 
-    // get user info of main contact.
-    $config = CRM_Core_Config::singleton();
-    $config->doNotResetCache = 1;
+      $join = CRM_Dedupe_Merger::getJoinOnDedupeTable();
+      $where = "de.id IS NULL";
 
-    $viewUser = CRM_Core_Permission::check('access user profiles');
-    $mainUfId = CRM_Core_BAO_UFMatch::getUFId($cid);
-    $mainUser = NULL;
-    if ($mainUfId) {
-      // d6 compatible
-      if ($config->userSystem->is_drupal == '1') {
-        $mainUser = user_load($mainUfId);
-      }
-      elseif ($config->userFramework == 'Joomla') {
-        $mainUser = JFactory::getUser($mainUfId);
-      }
+      $pos = CRM_Core_BAO_PrevNextCache::getPositions($cacheKey, $this->_cid, $this->_oid, $this->_mergeId, $join, $where, $flip);
 
-      $this->assign('mainUfId', $mainUfId);
-      $this->assign('mainUfName', $mainUser ? $mainUser->name : NULL);
-    }
+      // get user info of main contact.
+      $config = CRM_Core_Config::singleton();
+      $config->doNotResetCache = 1;
 
-    $flipUrl = CRM_Utils_System::url('civicrm/contact/merge',
-      "reset=1&action=update&cid={$oid}&oid={$cid}&rgid={$this->_rgid}&gid={$gid}"
-    );
-    if (!$flip) {
-      $flipUrl .= '&flip=1';
-    }
-    $this->assign('flip', $flipUrl);
-
-    $this->prev = $this->next = NULL;
-    foreach (array(
-               'prev',
-               'next',
-             ) as $position) {
-      if (!empty($pos[$position])) {
-        if ($pos[$position]['id1'] && $pos[$position]['id2']) {
-          $urlParams .= "&cid={$pos[$position]['id1']}&oid={$pos[$position]['id2']}&mergeId={$pos[$position]['mergeId']}&action=update";
-          $this->$position = CRM_Utils_System::url('civicrm/contact/merge', $urlParams);
-          $this->assign($position, $this->$position);
+      $mainUfId = CRM_Core_BAO_UFMatch::getUFId($this->_cid);
+      $mainUser = NULL;
+      if ($mainUfId) {
+        // d6 compatible
+        if ($config->userSystem->is_drupal == '1') {
+          $mainUser = user_load($mainUfId);
+        }
+        elseif ($config->userFramework == 'Joomla') {
+          $mainUser = JFactory::getUser($mainUfId);
         }
-      }
-    }
 
-    // get user info of other contact.
-    $otherUfId = CRM_Core_BAO_UFMatch::getUFId($oid);
-    $otherUser = NULL;
+        $this->assign('mainUfId', $mainUfId);
+        $this->assign('mainUfName', $mainUser ? $mainUser->name : NULL);
+      }
 
-    if ($otherUfId) {
-      // d6 compatible
-      if ($config->userSystem->is_drupal == '1') {
-        $otherUser = user_load($otherUfId);
+      $flipUrl = CRM_Utils_System::url('civicrm/contact/merge',
+        "reset=1&action=update&cid={$this->_oid}&oid={$this->_cid}&rgid={$this->_rgid}&gid={$gid}"
+      );
+      if (!$flip) {
+        $flipUrl .= '&flip=1';
       }
-      elseif ($config->userFramework == 'Joomla') {
-        $otherUser = JFactory::getUser($otherUfId);
+      $this->assign('flip', $flipUrl);
+
+      $this->prev = $this->next = NULL;
+      foreach (array(
+                 'prev',
+                 'next',
+               ) as $position) {
+        if (!empty($pos[$position])) {
+          if ($pos[$position]['id1'] && $pos[$position]['id2']) {
+            $urlParams .= "&cid={$pos[$position]['id1']}&oid={$pos[$position]['id2']}&mergeId={$pos[$position]['mergeId']}&action=update";
+            $this->$position = CRM_Utils_System::url('civicrm/contact/merge', $urlParams);
+            $this->assign($position, $this->$position);
+          }
+        }
       }
 
-      $this->assign('otherUfId', $otherUfId);
-      $this->assign('otherUfName', $otherUser ? $otherUser->name : NULL);
-    }
-
-    $cmsUser = ($mainUfId && $otherUfId) ? TRUE : FALSE;
-    $this->assign('user', $cmsUser);
-
-    $session = CRM_Core_Session::singleton();
+      // get user info of other contact.
+      $otherUfId = CRM_Core_BAO_UFMatch::getUFId($this->_oid);
+      $otherUser = NULL;
 
-    $rowsElementsAndInfo = CRM_Dedupe_Merger::getRowsElementsAndInfo($cid, $oid);
-    $main = $this->_mainDetails = $rowsElementsAndInfo['main_details'];
-    $other = $this->_otherDetails = $rowsElementsAndInfo['other_details'];
-
-    if ($main['contact_id'] != $cid) {
-      CRM_Core_Error::fatal(ts('The main contact record does not exist'));
-    }
+      if ($otherUfId) {
+        // d6 compatible
+        if ($config->userSystem->is_drupal == '1') {
+          $otherUser = user_load($otherUfId);
+        }
+        elseif ($config->userFramework == 'Joomla') {
+          $otherUser = JFactory::getUser($otherUfId);
+        }
 
-    if ($other['contact_id'] != $oid) {
-      CRM_Core_Error::fatal(ts('The other contact record does not exist'));
-    }
+        $this->assign('otherUfId', $otherUfId);
+        $this->assign('otherUfName', $otherUser ? $otherUser->name : NULL);
+      }
 
-    $this->assign('contact_type', $main['contact_type']);
-    $this->assign('main_name', $main['display_name']);
-    $this->assign('other_name', $other['display_name']);
-    $this->assign('main_cid', $main['contact_id']);
-    $this->assign('other_cid', $other['contact_id']);
-    $this->assign('rgid', $this->_rgid);
-
-    $this->_cid = $cid;
-    $this->_oid = $oid;
-
-    $this->addElement('checkbox', 'toggleSelect', NULL, NULL, array('class' => 'select-rows'));
-
-    $this->assign('mainLocBlock', json_encode($rowsElementsAndInfo['main_details']['location_blocks']));
-    $this->assign('locationBlockInfo', json_encode(CRM_Dedupe_Merger::getLocationBlockInfo()));
-    $this->assign('rows', $rowsElementsAndInfo['rows']);
-
-    // add elements
-    foreach ($rowsElementsAndInfo['elements'] as $element) {
-      // We could push this down to the getRowsElementsAndInfo function but it's
-      // already so overloaded - let's start moving towards doing form-things
-      // on the form.
-      if (substr($element[1], 0, 13) === 'move_location') {
-        $element[4] = array_merge(
-          (array) CRM_Utils_Array::value(4, $element, array()),
-          array('data-location' => substr($element[1], 14), 'data-is_location' => TRUE));
+      $cmsUser = ($mainUfId && $otherUfId) ? TRUE : FALSE;
+      $this->assign('user', $cmsUser);
+
+      $rowsElementsAndInfo = CRM_Dedupe_Merger::getRowsElementsAndInfo($this->_cid, $this->_oid);
+      $main = $this->_mainDetails = $rowsElementsAndInfo['main_details'];
+      $other = $this->_otherDetails = $rowsElementsAndInfo['other_details'];
+
+      $this->assign('contact_type', $main['contact_type']);
+      $this->assign('main_name', $main['display_name']);
+      $this->assign('other_name', $other['display_name']);
+      $this->assign('main_cid', $main['contact_id']);
+      $this->assign('other_cid', $other['contact_id']);
+      $this->assign('rgid', $this->_rgid);
+
+      $this->addElement('checkbox', 'toggleSelect', NULL, NULL, array('class' => 'select-rows'));
+
+      $this->assign('mainLocBlock', json_encode($rowsElementsAndInfo['main_details']['location_blocks']));
+      $this->assign('locationBlockInfo', json_encode(CRM_Dedupe_Merger::getLocationBlockInfo()));
+      $this->assign('rows', $rowsElementsAndInfo['rows']);
+
+      // add elements
+      foreach ($rowsElementsAndInfo['elements'] as $element) {
+        // We could push this down to the getRowsElementsAndInfo function but it's
+        // already so overloaded - let's start moving towards doing form-things
+        // on the form.
+        if (substr($element[1], 0, 13) === 'move_location') {
+          $element[4] = array_merge(
+            (array) CRM_Utils_Array::value(4, $element, array()),
+            array(
+              'data-location' => substr($element[1], 14),
+              'data-is_location' => TRUE,
+            ));
+        }
+        if (substr($element[1], 0, 15) === 'location_blocks') {
+          // @todo We could add some data elements here to make jquery manipulation more straight-forward
+          // @todo consider enabling if it is an add & defaulting to true.
+          $element[4] = array_merge((array) CRM_Utils_Array::value(4, $element, array()), array('disabled' => TRUE));
+        }
+        $this->addElement($element[0],
+          $element[1],
+          array_key_exists('2', $element) ? $element[2] : NULL,
+          array_key_exists('3', $element) ? $element[3] : NULL,
+          array_key_exists('4', $element) ? $element[4] : NULL,
+          array_key_exists('5', $element) ? $element[5] : NULL
+        );
       }
-      if (substr($element[1], 0, 15) === 'location_blocks') {
-        // @todo We could add some data elements here to make jquery manipulation more straight-forward
-        // @todo consider enabling if it is an add & defaulting to true.
-        $element[4] = array_merge((array) CRM_Utils_Array::value(4, $element, array()), array('disabled' => TRUE));
+
+      // add related table elements
+      foreach ($rowsElementsAndInfo['rel_table_elements'] as $relTableElement) {
+        $element = $this->addElement($relTableElement[0], $relTableElement[1]);
+        $element->setChecked(TRUE);
       }
-      $this->addElement($element[0],
-        $element[1],
-        array_key_exists('2', $element) ? $element[2] : NULL,
-        array_key_exists('3', $element) ? $element[3] : NULL,
-        array_key_exists('4', $element) ? $element[4] : NULL,
-        array_key_exists('5', $element) ? $element[5] : NULL
-      );
-    }
 
-    // add related table elements
-    foreach ($rowsElementsAndInfo['rel_table_elements'] as $relTableElement) {
-      $element = $this->addElement($relTableElement[0], $relTableElement[1]);
-      $element->setChecked(TRUE);
+      $this->assign('rel_tables', $rowsElementsAndInfo['rel_tables']);
+      $this->assign('userContextURL', CRM_Core_Session::singleton()
+        ->readUserContext());
+    }
+    catch (CRM_Core_Exception $e) {
+      CRM_Core_Error::statusBounce(ts($e->getMessage()));
     }
-
-    $this->assign('rel_tables', $rowsElementsAndInfo['rel_tables']);
-    $this->assign('userContextURL', $session->readUserContext());
   }
 
   public function addRules() {
diff --git a/CRM/Core/BAO/PrevNextCache.php b/CRM/Core/BAO/PrevNextCache.php
index ed1e367bd41d..b6e19a8c6b41 100644
--- a/CRM/Core/BAO/PrevNextCache.php
+++ b/CRM/Core/BAO/PrevNextCache.php
@@ -282,7 +282,7 @@ public static function retrieve($cacheKey, $join = NULL, $whereClause = NULL, $o
 
       if (!empty($select)) {
         $extraData = array();
-        foreach ($select as $dfield => $sfield) {
+        foreach ($select as $sfield) {
           $extraData[$sfield]  = $dao->$sfield;
         }
         $main[$count] = array(
diff --git a/CRM/Core/xml/Menu/Contact.xml b/CRM/Core/xml/Menu/Contact.xml
index 139466d2466f..092a67924b44 100644
--- a/CRM/Core/xml/Menu/Contact.xml
+++ b/CRM/Core/xml/Menu/Contact.xml
@@ -121,6 +121,7 @@
      <path>civicrm/contact/merge</path>
      <title>Merge Contact</title>
      <page_callback>CRM_Contact_Form_Merge</page_callback>
+     <access_arguments>merge duplicate contacts</access_arguments>
   </item>
   <item>
      <path>civicrm/contact/email</path>
diff --git a/CRM/Dedupe/Merger.php b/CRM/Dedupe/Merger.php
index 1905a85fdc0c..4f88b36282a6 100644
--- a/CRM/Dedupe/Merger.php
+++ b/CRM/Dedupe/Merger.php
@@ -1058,8 +1058,8 @@ public static function getRowsElementsAndInfo($mainId, $otherId, $checkPermissio
     $qfZeroBug = 'e8cddb72-a257-11dc-b9cc-0016d3330ee9';
     $fields = self::getMergeFieldsMetadata();
 
-    $main = self::getMergeContactDetails($mainId, 'main');
-    $other = self::getMergeContactDetails($otherId, 'main');
+    $main = self::getMergeContactDetails($mainId);
+    $other = self::getMergeContactDetails($otherId);
     $specialValues['main'] = self::getSpecialValues($main);
     $specialValues['other'] = self::getSpecialValues($other);
 
@@ -1165,7 +1165,7 @@ public static function getRowsElementsAndInfo($mainId, $otherId, $checkPermissio
         $values = civicrm_api3($blockName, 'get', $searchParams);
         if ($values['count']) {
           $cnt = 0;
-          foreach ($values['values'] as $index => $value) {
+          foreach ($values['values'] as $value) {
             $locations[$moniker][$blockName][$cnt] = $value;
             // Fix address display
             if ($blockName == 'address') {
@@ -1519,10 +1519,9 @@ public static function moveAllBelongings($mainId, $otherId, $migrationInfo, $che
         CRM_Core_DAO::$_nullObject, NULL, -1
       );
     }
-    $cgTree = &$treeCache[$migrationInfo['main_details']['contact_type']];
 
     $cFields = array();
-    foreach ($cgTree as $key => $group) {
+    foreach ($treeCache[$migrationInfo['main_details']['contact_type']] as $key => $group) {
       if (!isset($group['fields'])) {
         continue;
       }
@@ -1993,13 +1992,12 @@ public static function getMergeFieldsMetadata() {
    * Get the details of the contact to be merged.
    *
    * @param int $contact_id
-   * @param string $moniker
    *
    * @return array
    *
    * @throws CRM_Core_Exception
    */
-  public static function getMergeContactDetails($contact_id, $moniker) {
+  public static function getMergeContactDetails($contact_id) {
     $params = array(
       'contact_id' => $contact_id,
       'version' => 3,
@@ -2009,9 +2007,8 @@ public static function getMergeContactDetails($contact_id, $moniker) {
 
     // CRM-18480: Cancel the process if the contact is already deleted
     if (isset($result['values'][$contact_id]['contact_is_deleted']) && !empty($result['values'][$contact_id]['contact_is_deleted'])) {
-      throw new CRM_Core_Exception(ts('Cannot merge because the \'%1\' contact (ID %2) has been deleted.', array(
-        1 => $moniker,
-        2 => $contact_id,
+      throw new CRM_Core_Exception(ts('Cannot merge because one contact (ID %1) has been deleted.', array(
+        1 => $contact_id,
       )));
     }