httpd.conf on Windows: can’t locate API model structure `php8_module`

I had exactly the same problem. I found a solution here.

As it turned out in PHP 8 we should not use php8_module as we would expect, but only plain php_module

So the loader line should look like this:

LoadModule php_module "c:/Program Files/PHP/php-8.0.0RC2/php8apache2_4.dll"