diff --git a/documentation/zensical.toml b/documentation/zensical.toml
index e5f38ff24..1e9c42188 100644
--- a/documentation/zensical.toml
+++ b/documentation/zensical.toml
@@ -39,6 +39,7 @@ nav = [
         ]}
     ]},
     {"Developers" = [
+        {"Codabench Basic Installation Guide" = "Developers_and_Administrators/Codabench-Installation.md"},
         {"Codabench Docker Architecture" = "Developers_and_Administrators/Codabench-Architecture.md"},
         {"Submission Docker Container Layout" = "Developers_and_Administrators/Submission-Docker-Container-Layout.md"},
         {"Submission Process Overview" = "Developers_and_Administrators/Submission-Process-Overview.md"},
@@ -49,7 +50,6 @@ nav = [
 
     ]},
     {"Self-Hosters" = [
-        {"Codabench Basic Installation Guide" = "Developers_and_Administrators/Codabench-Installation.md"},
         {"How to Deploy a Server" = "Developers_and_Administrators/How-to-deploy-Codabench-on-your-server.md"},
         {"Administrative Procedures" = "Developers_and_Administrators/Administrator-procedures.md"},
         {"Backups - Automating Creation and Restoring" = "Developers_and_Administrators/Creating-and-Restoring-from-Backup.md"},
diff --git a/src/apps/competitions/models.py b/src/apps/competitions/models.py
index e5facb4fc..f919ae432 100644
--- a/src/apps/competitions/models.py
+++ b/src/apps/competitions/models.py
@@ -536,9 +536,10 @@ def soft_delete(self):
             detail.delete()  # Remove record from DB
 
         # Clear the data field if no other submissions are using it
-        other_submissions_using_data = Submission.objects.filter(data=self.data).exclude(pk=self.pk).exists()
-        if not other_submissions_using_data:
-            self.data.delete()
+        if self.data:
+            other_submissions_using_data = Submission.objects.filter(data=self.data).exclude(pk=self.pk).exists()
+            if not other_submissions_using_data:
+                self.data.delete()
 
         # Clear the data field for this submission
         self.data = None
@@ -554,11 +555,12 @@ def soft_delete(self):
     def delete(self, **kwargs):
 
         # Check if any other submissions are using the same data
-        other_submissions_using_data = Submission.objects.filter(data=self.data).exclude(pk=self.pk).exists()
+        if self.data:
+            other_submissions_using_data = Submission.objects.filter(data=self.data).exclude(pk=self.pk).exists()
 
-        if not other_submissions_using_data:
-            # If no other submissions are using the same data, delete it
-            self.data.delete()
+            if not other_submissions_using_data:
+                # If no other submissions are using the same data, delete it
+                self.data.delete()
 
         # Also clean up details on delete
         self.details.all().delete()
diff --git a/src/apps/profiles/views.py b/src/apps/profiles/views.py
index 81c8dc1de..161fd5ffe 100644
--- a/src/apps/profiles/views.py
+++ b/src/apps/profiles/views.py
@@ -290,7 +290,7 @@ def log_in(request):
             try:
                 user = User.objects.get((Q(username=username) | Q(email=username)) & Q(is_deleted=False))
             except User.DoesNotExist:
-                messages.error(request, "User does not exist!")
+                messages.error(request, "Invalid login/password")
             else:
                 # Authenticate user with credentials
                 user = authenticate(username=username, password=password)
@@ -307,7 +307,7 @@ def log_in(request):
                     else:
                         context['activation_error'] = "Your account is not activated. Please check your email for the activation link"
                 else:
-                    messages.error(request, "Wrong Credentials!")
+                    messages.error(request, "Invalid login/password")
         else:
             context['form'] = form
 
diff --git a/src/settings/base.py b/src/settings/base.py
index d2698bb2a..3f39a2448 100644
--- a/src/settings/base.py
+++ b/src/settings/base.py
@@ -92,7 +92,6 @@
     'django.contrib.messages.middleware.MessageMiddleware',
     'django.middleware.clickjacking.XFrameOptionsMiddleware',
     # 'corsheaders.middleware.CorsMiddleware', # BB
-    'django.middleware.common.CommonMiddleware',
     'middleware.BlockBannedUsersMiddleware'
 )
 
diff --git a/src/static/riot/competitions/detail/submission_manager.tag b/src/static/riot/competitions/detail/submission_manager.tag
index 441a6cf52..3f41a69eb 100644
--- a/src/static/riot/competitions/detail/submission_manager.tag
+++ b/src/static/riot/competitions/detail/submission_manager.tag
@@ -123,8 +123,15 @@
                     </a>
                 </td>
                 <!--  Show Action buttons when submission is not soft deleted  -->
-                <!--  Otherwise show empty <td>  -->
-                <td if="{ submission.is_soft_deleted }"></td>
+                <!--  For soft-deleted submissions, organizers can still hard-delete  -->
+                <td if="{ submission.is_soft_deleted }">
+                    <virtual if="{ opts.admin }">
+                        <span data-tooltip="Delete Submission" data-inverted=""
+                            onclick="{ delete_submission.bind(this, submission) }">
+                            <i class="icon red trash alternate"></i>
+                        </span>
+                    </virtual>
+                </td>
                 <td class="center aligned" if="{ !submission.is_soft_deleted }">
                     <virtual if="{ opts.admin}">
                         <!-- run/rerun submission -->