diff --git a/frontend/src/components/common/account.js b/frontend/src/components/common/account.js
index 065bf1ee63..cf90c67752 100644
--- a/frontend/src/components/common/account.js
+++ b/frontend/src/components/common/account.js
@@ -77,6 +77,7 @@ class Account extends Component {
           quotaUsage: Utils.bytesToSize(resp.data.usage),
           quotaTotal: Utils.bytesToSize(resp.data.total),
           isStaff: resp.data.is_staff,
+          isInstAdmin: resp.data.is_inst_admin,
           isOrgStaff: resp.data.is_org_staff === 1 ? true : false,
           showInfo: !this.state.showInfo,
         });
@@ -91,29 +92,47 @@ class Account extends Component {
   }
 
   renderMenu = () => {
-    if (this.state.isStaff && this.props.isAdminPanel) {
-      return (
-        <a href={siteRoot} title={gettext('Exit Admin Panel')} className="item">{gettext('Exit Admin Panel')}</a>
-      );
+    let data;
+    const { isStaff, isOrgStaff, isInstAdmin } = this.state;
+
+    if (this.props.isAdminPanel) {
+      if (isStaff) {
+        data = {
+          url: siteRoot,
+          text: gettext('Exit System Admin')
+        };
+      } else if (isOrgStaff) {
+        data = {
+          url: siteRoot,
+          text: gettext('Exit Organization Admin')
+        };
+      } else if (isInstAdmin) {
+        data = {
+          url: siteRoot,
+          text: gettext('Exit Institution Admin')
+        };
+      }
+
+    } else {
+      if (isStaff) {
+        data = {
+          url: `${siteRoot}sys/useradmin/`,
+          text: gettext('System Admin')
+        };
+      } else if (isOrgStaff) {
+        data = {
+          url: `${siteRoot}org/useradmin/`,
+          text: gettext('Organization Admin')
+        };
+      } else if (isInstAdmin) {
+        data = {
+          url: `${siteRoot}inst/useradmin/`,
+          text: gettext('Institution Admin')
+        };
+      }
     }
 
-    if (this.state.isOrgStaff && this.props.isAdminPanel) {
-      return (
-        <a href={siteRoot} title={gettext('Exit Organization Admin')} className="item">{gettext('Exit Organization Admin')}</a>
-      );
-    }
-
-    if (this.state.isStaff) {
-      return (
-        <a href={siteRoot + 'sys/useradmin/'} title={gettext('System Admin')} className="item">{gettext('System Admin')}</a>
-      );
-    }
-
-    if (this.state.isOrgStaff) {
-      return (
-        <a href={siteRoot + 'org/useradmin/'} title={gettext('Organization Admin')} className="item">{gettext('Organization Admin')}</a>
-      );
-    }
+    return data && <a href={data.url} title={data.text} className="item">{data.text}</a>;
   }
 
   renderAvatar = () => {
diff --git a/frontend/src/components/main-side-nav.js b/frontend/src/components/main-side-nav.js
index 4dfea55b9d..a080465f0a 100644
--- a/frontend/src/components/main-side-nav.js
+++ b/frontend/src/components/main-side-nav.js
@@ -8,7 +8,7 @@ import { Utils } from '../utils/utils';
 import toaster from './toast';
 import Group from '../models/group';
 
-import { canViewOrg, isDocs, isPro } from '../utils/constants';
+import { canViewOrg, isDocs, isPro, customNavItems } from '../utils/constants';
 
 const propTypes = {
   currentTab: PropTypes.oneOfType([PropTypes.string, PropTypes.number]).isRequired,
@@ -164,6 +164,21 @@ class MainSideNav extends React.Component {
     );
   }
 
+  renderCustomNavItems() {
+    return (
+      customNavItems.map((item, idx) => {
+        return (
+          <li key={idx} className="nav-item">
+            <a href={item.link} className="nav-link ellipsis" title={item.desc}>
+              <span className={item.icon} aria-hidden="true"></span>
+              <span className="nav-text">{item.desc}</span>
+            </a>
+          </li>
+        );
+      })
+    );
+  }
+
   render() {
     let showActivity = isDocs || isPro; 
     return (
@@ -261,6 +276,7 @@ class MainSideNav extends React.Component {
               </a>
               {this.renderSharedAdmin()}
             </li>
+            {customNavItems && this.renderCustomNavItems()}
           </ul>
         </div>
 
diff --git a/frontend/src/utils/constants.js b/frontend/src/utils/constants.js
index ede75f065f..6a66be5c13 100644
--- a/frontend/src/utils/constants.js
+++ b/frontend/src/utils/constants.js
@@ -54,6 +54,7 @@ export const repoPasswordMinLength = window.app.pageOptions.repoPasswordMinLengt
 export const canAddPublicRepo = window.app.pageOptions.canAddPublicRepo;
 export const canInvitePeople = window.app.pageOptions.canInvitePeople;
 export const canLockUnlockFile = window.app.pageOptions.canLockUnlockFile;
+export const customNavItems = window.app.pageOptions.customNavItems;
 
 export const curNoteMsg = window.app.pageOptions.curNoteMsg;
 export const curNoteID = window.app.pageOptions.curNoteID;
diff --git a/media/office-template/empty.docx b/media/office-template/empty.docx
index 939e7d7f9b..f5ea6976e7 100644
Binary files a/media/office-template/empty.docx and b/media/office-template/empty.docx differ
diff --git a/seahub/api2/endpoints/repos.py b/seahub/api2/endpoints/repos.py
index 801502376f..78fc15707f 100644
--- a/seahub/api2/endpoints/repos.py
+++ b/seahub/api2/endpoints/repos.py
@@ -351,8 +351,17 @@ class RepoView(APIView):
 
         repo = seafile_api.get_repo(repo_id)
         if not repo:
-            error_msg = 'Library %s not found.' % repo_id
-            return api_error(status.HTTP_404_NOT_FOUND, error_msg)
+            # for case of `seafile-data` has been damaged
+            # no `repo object` will be returned from seafile api
+            # delete the database record anyway
+            try:
+                seafile_api.remove_repo(repo_id)
+            except Exception as e:
+                logger.error(e)
+                error_msg = 'Internal Server Error'
+                return api_error(status.HTTP_500_INTERNAL_SERVER_ERROR, error_msg)
+
+            return Response({'success': True})
 
         # check permission
         username = request.user.username
diff --git a/seahub/api2/views.py b/seahub/api2/views.py
index 1ab9930542..9da3011211 100644
--- a/seahub/api2/views.py
+++ b/seahub/api2/views.py
@@ -329,6 +329,9 @@ class AccountInfo(APIView):
         info['institution'] = p.institution if p and p.institution else ""
         info['is_staff'] = request.user.is_staff
 
+        if getattr(settings, 'MULTI_INSTITUTION', False):
+            info['is_inst_admin'] = request.user.inst_admin
+
         interval = UserOptions.objects.get_file_updates_email_interval(email)
         info['email_notification_interval'] = 0 if interval is None else interval
         return info
diff --git a/seahub/institutions/middleware.py b/seahub/institutions/middleware.py
index 6a609e6f46..b00c76c71a 100644
--- a/seahub/institutions/middleware.py
+++ b/seahub/institutions/middleware.py
@@ -16,6 +16,7 @@ class InstitutionMiddleware(object):
         try:
             inst_admin = InstitutionAdmin.objects.get(user=username)
         except InstitutionAdmin.DoesNotExist:
+            request.user.inst_admin = False
             return None
 
         request.user.institution = inst_admin.institution
diff --git a/seahub/notifications/management/commands/send_file_updates.py b/seahub/notifications/management/commands/send_file_updates.py
index 65ba0614fa..c8be42b028 100644
--- a/seahub/notifications/management/commands/send_file_updates.py
+++ b/seahub/notifications/management/commands/send_file_updates.py
@@ -63,8 +63,10 @@ class Command(BaseCommand):
 
     def handle(self, *args, **options):
         logger.debug('Start sending file updates emails...')
+        self.stdout.write('[%s] Start sending file updates emails...' % str(datetime.now()))
         self.do_action()
         logger.debug('Finish sending file updates emails.\n')
+        self.stdout.write('[%s] Finish sending file updates emails.\n\n' % str(datetime.now()))
 
     def get_avatar(self, username, default_size=32):
         img_tag = avatar(username, default_size)
@@ -176,9 +178,6 @@ class Command(BaseCommand):
         return (op, details)
 
     def do_action(self):
-        today = datetime.utcnow().replace(hour=0).replace(minute=0).replace(
-            second=0).replace(microsecond=0)
-
         emails = []
         user_file_updates_email_intervals = []
         for ele in UserOptions.objects.filter(
@@ -190,6 +189,7 @@ class Command(BaseCommand):
                 emails.append(ele.email)
             except Exception as e:
                 logger.error(e)
+                self.stderr.write('[%s]: %s' % (str(datetime.now()), e))
                 continue
 
         user_last_emailed_time_dict = {}
@@ -201,6 +201,7 @@ class Command(BaseCommand):
                     ele.option_val, "%Y-%m-%d %H:%M:%S")
             except Exception as e:
                 logger.error(e)
+                self.stderr.write('[%s]: %s' % (str(datetime.now()), e))
                 continue
 
         for (username, interval_val) in user_file_updates_email_intervals:
@@ -212,14 +213,18 @@ class Command(BaseCommand):
             translation.activate(user_language)
             logger.debug('Set language code to %s for user: %s' % (
                 user_language, username))
-            self.stdout.write('[%s] Set language code to %s' % (
-                str(datetime.now()), user_language))
+            self.stdout.write('[%s] Set language code to %s for user: %s' % (
+                str(datetime.now()), user_language, username))
 
-            # get last_emailed_time if any, defaults to today
-            last_emailed_time = user_last_emailed_time_dict.get(username, today)
+            # get last_emailed_time if any, defaults to today 00:00:00.0
+            last_emailed_time = user_last_emailed_time_dict.get(username, None)
             now = datetime.utcnow().replace(microsecond=0)
-            if (now - last_emailed_time).seconds < interval_val:
-                continue
+            if not last_emailed_time:
+                last_emailed_time = datetime.utcnow().replace(hour=0).replace(
+                                    minute=0).replace(second=0).replace(microsecond=0)
+            else:
+                if (now - last_emailed_time).total_seconds() < interval_val:
+                    continue
 
             # get file updates(from: last_emailed_time, to: now) for repos
             # user can access
@@ -245,6 +250,9 @@ class Command(BaseCommand):
                 logger.error('Failed to format mail content for user: %s' %
                              username)
                 logger.error(e, exc_info=True)
+                self.stderr.write('[%s] Failed to format mail content for user: %s' %
+                                  (str(datetime.now()), username))
+                self.stderr.write('[%s]: %s' % (str(datetime.now()), e))
                 continue
 
             nickname = email2nickname(username)
@@ -263,11 +271,13 @@ class Command(BaseCommand):
                 # set new last_emailed_time
                 UserOptions.objects.set_file_updates_last_emailed_time(
                     username, now)
+                self.stdout.write('[%s] Successful to send email to %s' %
+                                  (str(datetime.now()), contact_email))
             except Exception as e:
                 logger.error('Failed to send email to %s, error detail: %s' %
                              (contact_email, e))
                 self.stderr.write('[%s] Failed to send email to %s, error '
-                                  'detail: %s' % (str(now), contact_email, e))
+                                  'detail: %s' % (str(datetime.now()), contact_email, e))
             finally:
                 # reset lang
                 translation.activate(cur_language)
diff --git a/seahub/settings.py b/seahub/settings.py
index 6c209c2a4a..904064a669 100644
--- a/seahub/settings.py
+++ b/seahub/settings.py
@@ -902,3 +902,14 @@ if ENABLE_REMOTE_USER_AUTHENTICATION:
 
 if ENABLE_OAUTH or ENABLE_WORK_WEIXIN:
     AUTHENTICATION_BACKENDS += ('seahub.oauth.backends.OauthRemoteUserBackend',)
+
+#####################
+# Custom Nav Items  #
+#####################
+# an example:
+# CUSTOM_NAV_ITEMS = [
+#     {'icon': 'sf2-icon-star',
+#      'desc': 'test custom name',
+#      'link': 'http://127.0.0.1:8000/shared-libs/',
+#      },
+# ]
diff --git a/seahub/templates/base_for_react.html b/seahub/templates/base_for_react.html
index aac4ad9c4b..60825012f3 100644
--- a/seahub/templates/base_for_react.html
+++ b/seahub/templates/base_for_react.html
@@ -91,9 +91,10 @@
             repoPasswordMinLength: {{repo_password_min_length}},
             canAddPublicRepo: {% if can_add_public_repo %} true {% else %} false {% endif %},
             canInvitePeople: {% if enable_guest_invitation and user.permissions.can_invite_guest %} true {% else %} false {% endif %},
+            customNavItems: {% if custom_nav_items %} JSON.parse('{{ custom_nav_items | escapejs }}') {% else %} {{'[]'}} {% endif %},
 
             {% if request.user.is_authenticated and request.cur_note %}
-            curNoteMsg: '{{ request.cur_note.message|urlize }}',
+            curNoteMsg: '{{ request.cur_note.message|urlize|escapejs }}',
             curNoteID: '{{ request.cur_note.id }}',
             {% endif %}
         }
diff --git a/seahub/views/__init__.py b/seahub/views/__init__.py
index 598265dce0..83fab2724e 100644
--- a/seahub/views/__init__.py
+++ b/seahub/views/__init__.py
@@ -63,6 +63,7 @@ from seahub.onlyoffice.settings import ENABLE_ONLYOFFICE
 from seahub.constants import HASH_URLS, PERMISSION_READ
 
 LIBRARY_TEMPLATES = getattr(settings, 'LIBRARY_TEMPLATES', {})
+CUSTOM_NAV_ITEMS = getattr(settings, 'CUSTOM_NAV_ITEMS', '')
 
 from constance import config
 
@@ -1267,7 +1268,8 @@ def react_fake_view(request, **kwargs):
         'is_email_configured': IS_EMAIL_CONFIGURED,
         'can_add_public_repo': request.user.permissions.can_add_public_repo(),
         'folder_perm_enabled': folder_perm_enabled,
-        'file_audit_enabled' : FILE_AUDIT_ENABLED
+        'file_audit_enabled' : FILE_AUDIT_ENABLED,
+        'custom_nav_items' : json.dumps(CUSTOM_NAV_ITEMS),
     })
 
 @login_required