[Solved] What is wrong with this Express error handling middleware? app.use((err, req, res) => { res.status(500).send('Error: ' + err.message); }); | Node.js

Node.js - Error Handling Patterns

What is wrong with this Express error handling middleware?

app.use((err, req, res) => {
  res.status(500).send('Error: ' + err.message);
});

AIt is missing the 'next' parameter, so Express won't recognize it as error middleware.

BIt should not use res.status(500) inside error middleware.

CThe error parameter should be named 'error' instead of 'err'.

DIt should be placed before route handlers, not after.

Step-by-Step Solution

Solution:

Step 1: Check middleware parameters
Express error middleware requires four parameters: err, req, res, next.
Step 2: Identify missing parameter
This middleware has only three parameters, missing 'next', so Express treats it as normal middleware, not error handler.
Final Answer:
It is missing the 'next' parameter, so Express won't recognize it as error middleware. -> Option A
Quick Check:
Error middleware must have 4 params (err, req, res, next) [OK]

Quick Trick: Error middleware always needs 4 parameters [OK]

Common Mistakes:

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What is wrong with this Express error handling middleware?