For developers and anyone stuck on an error

Paste an error, get the cause and the fix

The Error Message Explainer reads an error message or stack trace and explains what went wrong in plain English, the most likely causes ranked, the fix with corrected code, how to confirm it worked and how to prevent it next time. It works for JavaScript, TypeScript, React, Next.js, PHP, WordPress, Python and most other stacks.

Free, no sign-up
Results in about 30 seconds
10 runs a day
Input not stored

mohitgoyal.in/tools/error-message-explainerFree · 10 runs a day

Error Message Explainer

The cause and the fix for any error

Result· Ready

Your result will appear here

Fill in the form, or press Try an example to see what you get:

What the error means, in plain English
The most likely causes, ranked
The fix, with corrected code
How to confirm it's fixed
How to prevent it next time

How it works

How to use the Error Message Explainer

Paste the error
The full message and stack trace, exactly as your terminal or browser console shows it.
Add the code if you can
The function or file the error points to makes the fix exact. Remove secrets first.
Apply the fix
Copy the corrected code, then follow the check to confirm it's solved.

What you get

Inside every result

What the error means, in plain English
The most likely causes, ranked
The fix, with corrected code
How to confirm it's fixed
How to prevent it next time

Who it's for

Built for

Developers stuck on an unfamiliar error
WordPress site owners facing a critical error
Students learning to code
Founders debugging their own MVP

How to read a stack trace

The first line names the error type and message. The lines below list the functions that were running, most recent first. The first line that points to your own file, not a library, is usually where to look.

Line and column numbers like ProductList.tsx:14:23 tell you exactly where it failed: file, line 14, character 23.

Paste the code for an exact fix

An error message alone gives the likely causes. With the code the error points to, the explainer can name the exact line and write the corrected version. Paste the smallest piece that still shows the problem.

Keep secrets out

Never paste API keys, passwords, tokens or customer data. Replace them with placeholders like YOUR_API_KEY. Nothing is stored on this site, but secrets shouldn't leave your machine at all.

Questions

Frequently asked

Which languages does it support?+

Most of them: JavaScript, TypeScript, React, Next.js, Node.js, PHP, WordPress, Python, Java, Go, SQL and more. Naming your framework and version makes the answer sharper.

What does 'Cannot read properties of undefined' mean?+

Your code tried to use a property of something that doesn't exist yet, often data that hasn't loaded or an API response with a different shape than expected. Paste it in and the explainer will point at the exact cause.

Is it safe to paste my code?+

Nothing is stored on this site. Still, remove API keys, passwords and customer data before pasting any code into any online tool.

What if the fix doesn't work?+

Run it again with the new error message and the updated code. Errors often change once the first problem is solved, which is progress.

Is this tool free?+

Yes. Every tool on this site is free with no sign-up. Each visitor gets 10 runs per tool per day, which keeps the tools fast and available for everyone.

Is what I paste saved or shared?+

No. Your input is sent to the AI model (Claude by Anthropic) only to generate your result, and it is not stored on this site. Still, do not paste passwords, financial details or anything confidential.

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