I am having 500 internal server error in checkout page in woocommerce. While order for simple product then it's work fine, but when use with bookable product then booking order is saved in admin panel, mail is also send, but order recipt not display in checkout page, having error in this wc-ajax=checkout, checked in console.
A most popular problem of 500 internal server error is some fatal errors in backend part of your website. To find, where you got problem, you should to remove this from your wp-config.php file:
define( 'WP_DEBUG', false );
And instead of it add this code:
define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );
The next step will be to go to the page of your website, where you're getting 500 internal server error.
After open this file {your-website-folder}/wp-content/debug.log. Here you'll find all errors, which caused php files. There you'll find Fatal Error: {why it occured and where} .
So, after this steps you'll have to open new question about your error.
Disable all plugin and try. If problem solved active plugin one by one and see what plugin conflict. Or you can go woocommerce tools and recreate default pages
来源：https://stackoverflow.com/questions/47854995/woocommerce-checkout-page-internal-server-error