Fatal error: Call to undefined function get_header() in index.php on line 1
fatal-error, undefined
Solution
It appears that you're trying to run a WordPress theme outside of an installation of WordPress.
You need to download a copy of WordPress, extract it into your `htdocs` folder (like you did with the theme), and then navigate to it in your browser.
After setting it up (just follow the instructions), you need to place that theme in `wp-content/themes` inside the WordPress install.
Then, you can change the theme to your new one in your WordPress administrator panel.
Problem
I have the same issue. I am totally new in PHP. I installed XAMPP and downloaded the hatch theme from WordPress. When I run index.php it gives me the following error "Fatal error: Call to undefined function get_header() in C:\xampp\htdocs\hatch\index.php on line 1" How can I fix this?