diff --git a/common/djangoapps/xmodule_django/models.py b/common/djangoapps/xmodule_django/models.py
index fdf7294f77..854c957876 100644
--- a/common/djangoapps/xmodule_django/models.py
+++ b/common/djangoapps/xmodule_django/models.py
@@ -2,11 +2,14 @@
 Useful django models for implementing XBlock infrastructure in django.
 """
 import warnings
+import logging
 
 from django.db import models
 from django.core.exceptions import ValidationError
 from opaque_keys.edx.keys import CourseKey, UsageKey, BlockTypeKey
 
+log = logging.getLogger(__name__)
+
 
 class NoneToEmptyManager(models.Manager):
     """
@@ -104,6 +107,16 @@ class OpaqueKeyField(models.CharField):
             return None
 
         if isinstance(value, basestring):
+            if value.endswith('\n'):
+                # An opaque key with a trailing newline has leaked into the DB.
+                # Log and strip the value.
+                log.warning(u'{}:{}:{}:to_python: Invalid key: {}. Removing trailing newline.'.format(
+                    self.model._meta.db_table,  # pylint: disable=protected-access
+                    self.name,
+                    self.KEY_CLASS.__name__,
+                    repr(value)
+                ))
+                value = value.rstrip()
             return self.KEY_CLASS.from_string(value)
         else:
             return value
@@ -123,7 +136,17 @@ class OpaqueKeyField(models.CharField):
             return ''  # CharFields should use '' as their empty value, rather than None
 
         assert isinstance(value, self.KEY_CLASS), "%s is not an instance of %s" % (value, self.KEY_CLASS)
-        return unicode(_strip_value(value))
+        serialized_key = unicode(_strip_value(value))
+        if serialized_key.endswith('\n'):
+            # An opaque key object serialized to a string with a trailing newline.
+            # Log the value - but do not modify it.
+            log.warning(u'{}:{}:{}:get_prep_value: Invalid key: {}.'.format(
+                self.model._meta.db_table,  # pylint: disable=protected-access
+                self.name,
+                self.KEY_CLASS.__name__,
+                repr(serialized_key)
+            ))
+        return serialized_key
 
     def validate(self, value, model_instance):
         """Validate Empty values, otherwise defer to the parent"""
diff --git a/lms/djangoapps/courseware/features/navigation.feature b/lms/djangoapps/courseware/features/navigation.feature
index 4c7320d7e5..1f40f8ee5e 100644
--- a/lms/djangoapps/courseware/features/navigation.feature
+++ b/lms/djangoapps/courseware/features/navigation.feature
@@ -4,10 +4,11 @@ Feature: LMS.Navigate Course
     In order to access courseware
     I want to be able to navigate through the content
 
-    Scenario: I can navigate to a section
-        Given I am viewing a course with multiple sections
-        When I navigate to a section
-        Then I see the content of the section
+# This scenario is flaky: See TNL-5315
+#    Scenario: I can navigate to a section
+#        Given I am viewing a course with multiple sections
+#        When I navigate to a section
+#        Then I see the content of the section
 
     Scenario: I can navigate to subsections
         Given I am viewing a section with multiple subsections
diff --git a/lms/templates/ccx/coach_dashboard.html b/lms/templates/ccx/coach_dashboard.html
index 4d0d942b3a..a7078a1eb2 100644
--- a/lms/templates/ccx/coach_dashboard.html
+++ b/lms/templates/ccx/coach_dashboard.html
@@ -89,9 +89,9 @@ from openedx.core.djangolib.js_utils import (
 
 <script>
   function setup_tabs() {
-    $(".instructor-nav a").on("click", function(event) {
+    $(".instructor-nav .btn-link").on("click", function(event) {
         event.preventDefault();
-        $(".instructor-nav a").removeClass("active-section");
+        $(".instructor-nav .btn-link").removeClass("active-section");
         var section_sel = "#" + $(this).attr("data-section");
         $("section.idash-section").hide();
         $(section_sel).show();
@@ -101,12 +101,12 @@ from openedx.core.djangolib.js_utils import (
     var url = document.URL,
         hashbang = url.indexOf('#!');
     if (hashbang != -1) {
-      var selector = '.instructor-nav a[data-section=' +
+      var selector = '.instructor-nav [data-section=' +
         url.substr(hashbang + 2) + ']';
       $(selector).click();
     }
     else {
-      $(".instructor-nav a").first().click();
+      $(".instructor-nav .btn-link").first().click();
     }
   }
 
diff --git a/requirements/edx/base.txt b/requirements/edx/base.txt
index ef0070e764..ae71d7527a 100644
--- a/requirements/edx/base.txt
+++ b/requirements/edx/base.txt
@@ -44,7 +44,7 @@ edx-lint==0.4.3
 edx-django-oauth2-provider==1.1.1
 edx-django-sites-extensions==2.0.1
 edx-oauth2-provider==1.1.3
-edx-opaque-keys==0.2.1
+edx-opaque-keys==0.3.3
 edx-organizations==0.4.1
 edx-rest-api-client==1.2.1
 edx-search==0.1.2