500 Internal Server Error in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this REST API error handler code?

Consider this Python Flask code snippet that handles errors:

from flask import Flask, jsonify
app = Flask(__name__)

@app.errorhandler(500)
def internal_error(error):
    return jsonify({'error': 'Internal Server Error'}), 500

@app.route('/cause_error')
def cause_error():
    1 / 0  # This will cause a ZeroDivisionError

if __name__ == '__main__':
    app.run()

What will the client receive when accessing /cause_error?

Rest API

from flask import Flask, jsonify
app = Flask(__name__)

@app.errorhandler(500)
def internal_error(error):
    return jsonify({'error': 'Internal Server Error'}), 500

@app.route('/cause_error')
def cause_error():
    1 / 0  # This will cause a ZeroDivisionError

if __name__ == '__main__':
    app.run()

A {"error": "Internal Server Error"} with HTTP status 500

B A JSON response with {'error': 'ZeroDivisionError'} and HTTP status 500

C A plain text message 'ZeroDivisionError' with HTTP status 200

D A server crash with no response sent to client

💡 Hint

Think about what the @app.errorhandler(500) decorator does.

The @app.errorhandler(500) decorator catches unhandled exceptions like ZeroDivisionError and returns the JSON response with status 500. So the client receives the JSON error message with HTTP 500.

🧠 Conceptual

intermediate

Why does a 500 Internal Server Error occur in REST APIs?

Which of the following best explains the cause of a 500 Internal Server Error in a REST API?

A The server encountered an unexpected condition that prevented it from fulfilling the request

B The client is not authorized to access the requested resource

C The requested resource was not found on the server

D The client sent a malformed request that the server cannot understand

💡 Hint

Think about whether the problem is on the client or server side.

A 500 Internal Server Error means the server failed due to an unexpected problem while processing a valid request. It is a server-side error, not caused by the client.

🔧 Debug

advanced

Identify the cause of 500 Internal Server Error in this Node.js Express code

Look at this Node.js Express code snippet:

const express = require('express');
const app = express();

app.get('/data', (req, res) => {
  const data = JSON.parse('{invalid json}');
  res.json(data);
});

app.listen(3000);

What will happen when a client requests /data?

A The server crashes and stops running

B The server responds with an empty JSON object {} and status 200

C The server responds with a 400 Bad Request error

D The server responds with a 500 Internal Server Error due to JSON.parse failure

💡 Hint

Consider what happens when JSON.parse receives invalid JSON.

JSON.parse throws a SyntaxError on invalid JSON. Since the error is not caught, Express returns a 500 Internal Server Error response.

📝 Syntax

advanced

Which code snippet correctly sends a 500 Internal Server Error in Express?

Choose the correct Express.js code to send a 500 Internal Server Error with a JSON message {"error": "Server failure"}:

A res.json(500, {error: 'Server failure'});

B res.status(500).json({error: 'Server failure'});

C res.send(500, {error: 'Server failure'});

D res.status(500).sendJson({error: 'Server failure'});

💡 Hint

Check the Express.js method chaining syntax for setting status and sending JSON.

In Express, res.status(500).json(...) sets the HTTP status code and sends a JSON response. Other options use invalid or deprecated syntax.

🚀 Application

expert

How to safely handle unexpected errors to avoid 500 Internal Server Errors in REST APIs?

You are designing a REST API. Which approach best prevents unhandled exceptions causing 500 Internal Server Errors?

A Return HTTP 200 status with error details in the response body for all errors

B Ignore errors and let the server crash to restart cleanly

C Wrap all code in try-catch blocks and return meaningful error responses for known errors

D Use client-side validation only and assume server code never fails

💡 Hint

Think about how to handle errors gracefully on the server side.

Wrapping code in try-catch blocks allows catching errors and returning controlled responses, preventing unexpected 500 errors and improving API reliability.