Declaration of Illuminate\Container\Container::get($id) must be compatible with Psr\Container\ContainerInterface::get(string $id)
Stefan Izdrail
Founder & Senior Architect · 2026-06-29
The error message "Declaration of Illuminate\Container\Container::get($id) must be compatible with Psr\Container\ContainerInterface::get(string $id)" can often result from an inconsistency in package versions, and the following steps may help you troubleshoot such issues. Although this example is from a Laravel 8 project, these concepts are applicable to Laravel projects of other versions.
In Laravel, the Container class handles dependency injection among classes. When you call Illuminate\Container\Container::get($id), it should return an instance or object based on the given $id. The Psr\Container\ContainerInterface is a standard interface that defines the minimum set of methods an object must implement to be considered a container.
The error message suggests an incongruity between the method signatures of two classes: Illuminate\Container\Container::get($id) and Psr\Container\ContainerInterface::get(string $id). This inconsistency might result from incorrect package versions or conflicting dependencies. The first method expects a single parameter, while the second has an additional type hint for the argument to be a string.
To resolve this issue, you can try these steps:
1. Check your Laravel application's composer.json file. Ensure that all Laravel-related packages are at their latest versions and there are no conflicting dependencies. You may need to update your composer with the following command:composer update.
2. Clear your cache: Remove the vendor/cache directory (if present) and delete all contents of the public/storage/cache folder, then run php artisan config:clear and php artisan optimize to flush the application's configurations and compiler cache.
3. Review your composer.lock file in comparison with your composer.json file. Ensure that all dependencies are as expected and there are no missing or conflicting packages. If needed, try to remove any unnecessary packages from composer.lock.
4. Use a dependency manager like Laravel Sail or Docker Compose to manage the application's dependencies more efficiently. This approach allows you to isolate your project from system-level environment issues and provides better consistency across environments.
5. Check the Laravel documentation for package version compatibility. You can also consult third-party blogs, forums, and the Laravel Slack community to get help with specific errors or troubleshooting steps.
6. If these measures don't resolve your issue, consider creating a fresh Laravel installation and copy over only the problematic codebase into the new project. This method helps narrow down the root cause of the error by eliminating potential conflicts between packages or customized configurations.
7. Once you've identified the source of the conflict, update the specific package (if necessary) or fix your code according to the guidelines provided in the Laravel documentation and third-party resources.
In summary, this error message indicates an inconsistency between method signatures for Illuminate\Container\Container::get($id) and Psr\Container\ContainerInterface::get(string $id). Addressing dependency conflicts or inconsistent package versions can help resolve the issue. By following these troubleshooting steps, you'll be better prepared to handle this and other Laravel container errors effectively.
Closing Thoughts:
The "Declaration of Illuminate\Container\Container::get($id) must be compatible with Psr\Container\ContainerInterface::get(string $id)" error message may seem intimidating at first, but it can often be resolved through a combination of updating, refreshing, and troubleshooting your Laravel project's dependencies. Remember to carefully analyze package versions, check for conflicts, and consult relevant resources for further guidance when encountering similar errors.