BACKEND_RESTART_GUIDE.md

Backend Restart Guide

Problem

The backend is running an old version without the Dijkstra endpoint.

Solution

Option 1: Use the Restart Script (Recommended)

cd backend
restart_server.bat

This will:

1. Kill any process on port 8000
2. Wait 2 seconds
3. Start the updated backend with Dijkstra support

Option 2: Manual Restart

1. Kill existing processes:

   • Open Task Manager (Ctrl+Shift+Esc)
   • Find "Python" processes
   • End all Python tasks

2. Start backend:

   cd backend
   venv\Scripts\activate
   uvicorn main:app --reload --host 127.0.0.1 --port 8000

Option 3: Use Different Port

If port 8000 is stuck, use port 8001:

1. Start on port 8001:

   cd backend
   venv\Scripts\activate
   uvicorn main:app --reload --host 127.0.0.1 --port 8001

2. Update frontend - Change all instances of:

   • http://127.0.0.1:8000 → http://127.0.0.1:8001
   • http://localhost:8000 → http://localhost:8001

Verify Backend is Running

Test the health endpoint:

curl http://127.0.0.1:8000/health

Should return: {"status":"OK"}

Test the Dijkstra endpoint exists:

curl http://127.0.0.1:8000/docs

Open in browser to see API documentation with the new /dijkstra-multi-route endpoint.

Test the Full Flow

1. Start backend (see above)
2. Start frontend: npm run dev
3. Go to http://localhost:3000/home
4. Enter route (e.g., "Kolkata" to "Salt Lake")
5. Toggle the Dijkstra checkbox
6. See routes change between modes

Troubleshooting

"Port 8000 already in use"

• Use restart_server.bat to force kill and restart
• Or use Task Manager to end Python processes
• Or use port 8001 instead

"Module not found" errors

Make sure you're in the virtual environment:

cd backend
venv\Scripts\activate

Backend starts but frontend can't connect

• Check CORS settings in backend/main.py
• Verify port matches in frontend code
• Check Windows Firewall isn't blocking

Dijkstra endpoint not found

• Backend is running old code
• Use restart_server.bat to reload
• Check console for import errors