Call out dependency on v2.11+ for upgrades

upgrade.sh

@@ -56,6 +56,22 @@ else
   echo "Skipping local dependencies (local_requirements.txt not found)"
 fi
 
+# Test schema migrations integrity
+COMMAND="python3 netbox/manage.py showmigrations"
+eval $COMMAND > /dev/null 2>&1 || {
+  echo "--------------------------------------------------------------------"
+  echo "ERROR: Database schema migrations are out of synchronization. (No"
+  echo "data has been lost.) If attempting to upgrade to NetBox v3.0 or"
+  echo "later, first upgrade to a v2.11 release to ensure schema migrations"
+  echo "have been correctly prepared. For further detail on the exact error,"
+  echo "run the following commands:"
+  echo ""
+  echo "    source ${VIRTUALENV}/bin/activate"
+  echo "    ${COMMAND}"
+  echo "--------------------------------------------------------------------"
+  exit 1
+}
+
 # Apply any database migrations
 COMMAND="python3 netbox/manage.py migrate"
 echo "Applying database migrations ($COMMAND)..."