How to Find Which API Endpoint Is Causing a Bug in Your Laravel and Vue App

When something breaks in your app and you are not sure which API is the problem, it can be frustrating. This guide is written in simple English for non-native speakers like me. I hope it helps you debug Laravel and Vue problems faster and with less stress.

Problem

You open your Vue frontend, and something is not working. A button does nothing, or data is missing on the page. You check the browser console — maybe you see an error, maybe not. You think:

“Which API is not working? Is it the backend or the frontend?”

Step 1: Open the Browser DevTools

Press F12 or right-click and select Inspect, then go to the Network tab.

Now reload the page.

You will see a list of requests going to your backend — usually with URLs like:

GET http://localhost/api/user

POST http://localhost/api/posts

Look for requests that are red or have a status like 500, 404, or 422. These are failed requests.

Step 2: Check the Response

Click on a red request. Inside the Response or Preview tab, you will see the message returned by Laravel. For example:

{ "message": "Unauthenticated" }

Or:

{

"error": "Invalid input in request body"

}

These messages tell you what the Laravel backend thinks is wrong.

Step 3: Check Laravel Logs

If the browser is not showing enough information, go to the backend.

Inside your Laravel project, run:

tail -f storage/logs/laravel.log

Now when you reload the page, Laravel will write any errors here. You will see the full stack trace, including which controller or API route is failing.

Step 4: Use Debug Tools Like Laravel Debugbar and Flare

Laravel Debugbar (Local Only)

You can install Laravel Debugbar to see API calls, routes, and queries in a bar at the bottom of the page:

composer require barryvdh/laravel-debugbar --dev

It works great for local development.

Flare (For Production and Teams)

Flare is a powerful tool to catch and log Laravel errors in real time. It gives you a clean UI and even shows which user caused the error, the request data, and file and line number.

To use it:

1. Create an account at Flare

2. Install it in your Laravel app:

   composer require facade/ignition

3. Set your API key in .env:

   FLARE_KEY=your-key-here

Flare is great if your app is in production and you want detailed bug reports without checking server logs every time.

Step 5: Check Your Vue Code

Sometimes the error is not from Laravel — but from your Vue code.

Open the Console tab in browser devtools. You might see:

Uncaught TypeError: Cannot read property 'name' of null

This means your frontend is trying to use data before the API response has arrived or when it is empty.

Use console.log(response) to check what the backend is sending.

Common Causes of API Bugs

Tips for Non-Native Developers

• Read error messages slowly and carefully. They usually tell you what is wrong.

• Do not panic. Debugging takes time.

• Use console.log() in Vue to check what data is coming back.

• Use Log::info() in Laravel to print things inside controller methods:

  Log::info('Request received:', $request->all());

• Use tools like Flare if you want clean bug reports with full context.

Conclusion

When your Laravel and Vue app is not working, and you are not sure which API is causing the bug, start with the browser Network tab, check Laravel logs, and inspect Vue console errors. Slowly, piece by piece, you will find the problem.

As a non-native English speaker, I know it can be hard to understand some error messages. But step by step, you can figure it out.

You do not have to be perfect — just keep going. Debugging is like solving a puzzle.