How to Fix 'Cannot assign requested address' Error in Docker with Xdebug and VS Code

Learn how to resolve the 'Cannot assign requested address' error when using Xdebug with Docker and VS Code. Follow our steps to fix your PHP development environment.
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How to Fix 'Cannot assign requested address' Error in Docker with Xdebug and VS Code

Encountering the 'Cannot assign requested address' error while using Docker, Xdebug, and VS Code can be frustrating, especially if you're in the middle of a PHP development session. This guide will walk you through understanding and resolving this error efficiently.

Understanding the Issue

When you're running a development environment using Docker, Docker Compose, and Xdebug, you might come across an issue where Xdebug cannot connect to your host machine. The error message typically looks like this:

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Common Causes

This error usually arises because Xdebug is trying to connect to a specific IP address that is not reachable from within the Docker container. Some common reasons for this could be:

The IP address specified in the Xdebug configuration is incorrect.

Network configurations that prevent the Docker container from accessing the host machine.

Incorrect or missing Docker Compose configurations.

Steps to Resolve the Error

Let’s delve into the most effective method to troubleshoot and fix this problem.

Verify Xdebug Configuration

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Update your Docker Compose File

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Test Connectivity with Telnet

Use telnet to verify the host port from your Docker container:

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If telnet connects successfully, the issue is likely with your Xdebug or Docker configuration. If it fails, it indicates a network or firewall problem.

Additional Tips

If the above steps do not resolve your issue, consider the following additional actions:

Restart your Docker service to clear cache and apply new configurations.

Ensure no firewall rules or antivirus software interfere with the connection.

Check the Docker and OS network settings for any conflicting configurations.

By confirming the appropriate configurations in both Xdebug and Docker, you can usually resolve the "Cannot assign requested address" error and get back to seamless PHP development.

Conclusion

Getting your Docker setup to work flawlessly with Xdebug and VS Code may require a little tweaking, but with this guide, you should be well on your way to resolving the "Cannot assign requested address" error. Happy debugging!