> ## Documentation Index
> Fetch the complete documentation index at: https://docs-staging-quickstart-revamp.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> Troubleshooting commons issues with your PHP applications.

# PHP: Troubleshooting your Auth0-PHP integration

The following is a list of issues you might see when using the Auth0 PHP library and how you might troubleshoot these issues.

**I'm getting an "Invalid State" exception when trying to log in.**

[State validation](/docs/secure/attack-protection/state-parameters) was added in 5.1.0 for improved security. By default, this uses session storage and will happen automatically if you are using a combination of `Auth0::login()` and any method which calls `Auth0::exchange()` in your callback.

If your users encounter this error:- Ensure your application is not accidentally invoking `Auth0::login()` more than once, which could invalidate the state stored on the end user's device.- The end user is using a modern browser on their device and not blocking cookies.

**I am getting** **`curl error 60: SSL certificate problem: self-signed certificate in certificate chain`** **on Windows**

This is a common issue with the latest PHP versions under **Windows OS** (it is related to an incompatibility between Windows and OpenSSL CA's database).

1. Download this CA database `https://curl.haxx.se/ca/cacert.pem` to `c:/cacert.pem`.
2. Edit your php.ini and add `openssl.cafile=c:/cacert.pem`. (It should point to the file you downloaded.)

**My host does not allow using Composer**

The PHP SDK requires Composer for maintaining dependencies (external PHP libraries). If Composer is now allowed to be installed globally on your host, you can still install it locally to run on your user shell account. Instructions for this can be found on the Composer website: \<[https://getcomposer.org/doc/00-intro.md#locally>](https://getcomposer.org/doc/00-intro.md#locally>)

## Learn more

* [PHP: Getting Started using Auth0-PHP](/docs/libraries/auth0-php)
* [PHP: Logging in, out, and returning user profiles with Auth0-PHP](/docs/libraries/auth0-php/auth0-php-basic-use)
* [PHP: Using the Authentication API with Auth0-PHP](/docs/libraries/auth0-php/using-the-authentication-api-with-auth0-php)
* [PHP: Using the Management API with Auth0-PHP](/docs/libraries/auth0-php/using-the-management-api-with-auth0-php)
* [PHP: Validating JWTs (JSON Web Tokens) with Auth0-PHP](/docs/libraries/auth0-php/validating-jwts-with-auth0-php)