Upgrading from Laravel 5.8 to Laravel 8 involves a significant version jump, and there have been some changes in Laravel 6, 7, and 8 that may affect your application. Therefore, it is important to review the Laravel upgrade documentation thoroughly and make sure to follow the recommended upgrade path.

Here are the general steps to upgrade from Laravel 5.8 to Laravel 8:

1. Review Laravel Upgrade Documentation: The Laravel documentation provides a comprehensive guide on how to upgrade from one version to another. Start by reviewing the Laravel upgrade documentation for each version starting from Laravel 5.8 to Laravel 6, 7, and then to Laravel 8. This will help you understand the changes you need to make to your application.

2. Upgrade to Laravel 6: Laravel 6 introduced some changes to the directory structure, so it is important to update your application to Laravel 6 first. Follow the Laravel upgrade documentation for Laravel 6 to upgrade your application.

3. Upgrade to Laravel 7: Laravel 7 introduced more changes, including the removal of some features, so it is important to review the Laravel upgrade documentation for Laravel 7 and make the necessary changes to your application.

4. Upgrade to Laravel 8: Once you have upgraded to Laravel 7, you can then upgrade to Laravel 8. Again, follow the Laravel upgrade documentation for Laravel 8 and make the necessary changes to your application.

5. Update Dependencies: After upgrading to Laravel 8, you will also need to update your dependencies, including any packages or libraries that you are using. Make sure to check the compatibility of these packages with Laravel 8 before updating them.

6. Test and Debug: After completing the upgrade process, make sure to thoroughly test your application to ensure that everything is working as expected. Debug any issues that may arise during the upgrade process.

7. Deploy: Once you have thoroughly tested your application, deploy it to your production environment.

Note that upgrading to Laravel 8 may also require you to update your PHP version to a supported version, such as PHP 7.4 or later.

It is also important to take backups of your application before upgrading and to ensure that you are working in a development environment before deploying any changes to your production environment.