Fix NotFoundError: Cannot GET /api/users/profile in Express

This error occurs when no route matches the requested path and method in Express, resulting in a default 404 HTML response. This usually means the route is misspelled, uses the wrong HTTP method, or the router is not mounted at the correct path. Fix it by adding a catch-all 404 handler and verifying your route definitions.

Reading the Stack Trace

Here's what each line means:

• Cannot GET /api/users/profile: Express could not find a route matching GET /api/users/profile and returned its default HTML 404 page.
• at /app/node_modules/express/lib/router/index.js:284:15: The Express router exhausted all registered routes without finding a match, falling through to the default 404 handler.
• at trim_prefix (/app/node_modules/express/lib/router/index.js:328:13): Express is trimming the route prefix while searching for a matching route handler in the router stack.

Common Causes

const router = express.Router();

// Route defined as /user/profile (singular)
router.get('/user/profile', (req, res) => {
  res.json({ user: req.user });
});

// Client requests /users/profile (plural) — no match

const usersRouter = require('./routes/users');

// Mounted at /user instead of /api/users
app.use('/user', usersRouter);

// Client requests /api/users/profile — no match

app.get('/api/users', (req, res) => {
  res.json({ users: [] });
});

// No 404 handler — Express sends default HTML error
app.listen(3000);

The Fix

Add a catch-all middleware after all route definitions that returns a JSON 404 response with the requested method and URL. This replaces Express's default HTML error page and helps API consumers understand what went wrong.

app.get('/api/users', (req, res) => {
  res.json({ users: [] });
});

app.listen(3000);

const usersRouter = express.Router();
usersRouter.get('/', (req, res) => res.json({ users: [] }));
usersRouter.get('/profile', (req, res) => res.json({ user: req.user }));

app.use('/api/users', usersRouter);

// Catch-all 404 handler — MUST be after all routes
app.use((req, res) => {
  res.status(404).json({
    error: 'Not Found',
    message: `Cannot ${req.method} ${req.originalUrl}`,
    availableEndpoints: ['/api/users', '/api/users/profile']
  });
});

app.listen(3000);

Testing the Fix

const request = require('supertest');
const express = require('express');

function createApp() {
  const app = express();
  const router = express.Router();
  router.get('/', (req, res) => res.json({ users: [] }));
  router.get('/profile', (req, res) => res.json({ user: { id: 1 } }));
  app.use('/api/users', router);
  app.use((req, res) => {
    res.status(404).json({ error: 'Not Found', message: `Cannot ${req.method} ${req.originalUrl}` });
  });
  return app;
}

describe('Route matching', () => {
  it('returns 200 for existing routes', async () => {
    const res = await request(createApp()).get('/api/users');
    expect(res.status).toBe(200);
  });

  it('returns 200 for /api/users/profile', async () => {
    const res = await request(createApp()).get('/api/users/profile');
    expect(res.status).toBe(200);
    expect(res.body.user.id).toBe(1);
  });

  it('returns JSON 404 for non-existent routes', async () => {
    const res = await request(createApp()).get('/api/nonexistent');
    expect(res.status).toBe(404);
    expect(res.body.error).toBe('Not Found');
    expect(res.body.message).toBe('Cannot GET /api/nonexistent');
  });
});

Run your tests:

npx jest --testPathPattern=route-not-found

Pushing Through CI/CD

git checkout -b fix/express-route-not-found,git add src/app.js src/routes/users.js src/__tests__/routeNotFound.test.js,git commit -m "fix: add JSON 404 catch-all handler for unmatched routes",git push origin fix/express-route-not-found

Your CI config should look something like this:

name: CI
on:
  pull_request:
    branches: [main]
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'
      - run: npm ci
      - run: npx jest --coverage
      - run: npm run lint

The Full Manual Process: 18 Steps

Here's every step you just went through to fix this one bug:

1. Notice the error alert or see it in your monitoring tool
2. Open the error dashboard and read the stack trace
3. Identify the file and line number from the stack trace
4. Open your IDE and navigate to the file
5. Read the surrounding code to understand context
6. Reproduce the error locally
7. Identify the root cause
8. Write the fix
9. Run the test suite locally
10. Fix any failing tests
11. Write new tests covering the edge case
12. Run the full test suite again
13. Create a new git branch
14. Commit and push your changes
15. Open a pull request
16. Wait for code review
17. Merge and deploy to production
18. Monitor production to confirm the error is resolved

Total time: 30-60 minutes. For one bug.

npm install bugstack-sdk

const { initBugStack } = require('bugstack-sdk')

initBugStack({ apiKey: process.env.BUGSTACK_API_KEY })

Deploying the Fix (Manual Path)

1. Run the test suite locally to confirm all routes resolve and unknown routes return JSON 404.
2. Open a pull request with the route and 404 handler changes.
3. Wait for CI checks to pass on the PR.
4. Have a teammate review and approve the PR.
5. Merge to main and verify route matching in staging before promoting to production.

Frequently Asked Questions