I created a new home page and set it as the home page in the reading section, but I get an error when typing in the home page url

WordPress recommends using PHP 7 or greater. So if you are using an ancient version of PHP, you should upgrade your server.

After you changed the name of your home page, did you go back to your display settings and check what is set there? Make sure that it is set to the page you actually want for a homepage. (And be sure to set something for your “blog” page, as well.)