> ## Documentation Index
> Fetch the complete documentation index at: https://ngrok.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Errors

> How ngrok error codes work, how to use them when troubleshooting or handling errors programmatically, and the most common errors.

## Philosophy

When you encounter an error while using ngrok, ngrok reports a globally unique error code.
Each error code corresponds to a specific location in ngrok's code, which helps ngrok quickly identify where something went wrong and helps you know exactly how to fix it.

When you report a bug or email ngrok support about an issue, include the unique error code if you have encountered one.
It helps ngrok diagnose and solve your issue much more quickly.

ngrok's error codes were also designed so that you can paste them into your
favorite search engine and immediately find a dedicated page with instructions
on how to fix your problem.

## Programmatic error handling

When you work with ngrok programmatically, ngrok returns these unique error codes
in a structured way so that you can write software which appropriately handles
different error conditions.

* [API Error Handling](https://ngrok.com/docs/api.md#errors)

## Common errors

You're more likely to run into some errors than others. The most common are
listed here to help make your troubleshooting easier.

| Code | Message |
| - | - |
| [ERR\_NGROK\_100](https://ngrok.com/docs/errors/err_ngrok_100) | Invalid metadata length: `VAL` bytes. Max: `MAX` |
| [ERR\_NGROK\_108](https://ngrok.com/docs/errors/err_ngrok_108) | Your account is limited to `MAX` simultaneous ngrok agent sessions. |
| [ERR\_NGROK\_1205](https://ngrok.com/docs/errors/err_ngrok_1205) | You failed to solve the CAPTCHA, please try again. |
| [ERR\_NGROK\_1226](https://ngrok.com/docs/errors/err_ngrok_1226) | You are disallowed from creating an ngrok account due to violation of the terms of service. |
| [ERR\_NGROK\_3004](https://ngrok.com/docs/errors/err_ngrok_3004) | The server returned an invalid or incomplete HTTP response. |
| [ERR\_NGROK\_3200](https://ngrok.com/docs/errors/err_ngrok_3200) | The endpoint `ENDPOINTURL` is offline. |
| [ERR\_NGROK\_3208](https://ngrok.com/docs/errors/err_ngrok_3208) | The ngrok account that was hosting this webpage has been banned for violation of ngrok's Terms of Service. |
| [ERR\_NGROK\_4011](https://ngrok.com/docs/errors/err_ngrok_4011) | Your password must be at least `LENGTH` characters. |
| [ERR\_NGROK\_4013](https://ngrok.com/docs/errors/err_ngrok_4013) | You may not create a new account because you are already a member of the free account "`ACCOUNT_NAME`". Upgrade or delete that account first before creating a new account. |
| [ERR\_NGROK\_4100](https://ngrok.com/docs/errors/err_ngrok_4100) | The email or password you entered is not valid. |
| [ERR\_NGROK\_4101](https://ngrok.com/docs/errors/err_ngrok_4101) | A user with the email address `EMAIL` already exists. |
| [ERR\_NGROK\_4108](https://ngrok.com/docs/errors/err_ngrok_4108) | Sign ups are disallowed for the email provider "`DOMAIN`". Sign up with a different email provider. |
| [ERR\_NGROK\_6022](https://ngrok.com/docs/errors/err_ngrok_6022) | Before you can serve HTML content, you must sign up for an ngrok account and install your authtoken. |
| [ERR\_NGROK\_6024](https://ngrok.com/docs/errors/err_ngrok_6024) | You are about to visit `HOSTPORT`, served by `SERVINGIP`. This website is served for free through ngrok.com. You should only visit this website if you trust whoever sent the link to you. |
| [ERR\_NGROK\_8012](https://ngrok.com/docs/errors/err_ngrok_8012) | Traffic successfully made it to the ngrok agent, but the agent failed to establish a connection to the upstream web service at `ADDR`. |

## All errors

Consult the [Errors Reference Documentation](https://ngrok.com/docs/errors/reference.md) for a
complete list of all of ngrok's error codes.

## Customize error pages for your traffic

To access and provide feedback on a development preview of custom error pages [Fill out the form](https://ngrok.com/new-features/custom-error-pages?ref=errordoc).


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