Uncaught exception 'Error' with message 'Call to undefined function get_the_block_template_html()

[harishtewari]

Error message:

Uncaught exception 'Error' with message 'Call to undefined function get_the_block_template_html()' in /var/www/wp-includes/template-canvas.php:12

​https://github.com/WordPress/wordpress-develop/pull/11784

https://core.trac.wordpress.org/ticket/65213

Trac ticket:

## Use of AI Tools
None

[westonruter]

The function should always exist there. If it doesn't for you, then something strange is going on. The fix isn't what you proposed in the attached PR.

This should probably get closed as invalid.

[westonruter]

Ah, well the issue is probably that someone is making a direct request to /wp-includes/template-canvas.php. Since this doesn't load WordPress, it doesn't require any other files that have this function defined. This is hardly unique to template-canvas.php, however. The same thing happens when attempting to access /wp-includes/template-canvas.php or many other PHP files in WordPress core. This has previously been reported. I'm closing this as a duplicate of #62722.

[szepe.viktor]

Try blocking requests to inner core files.
Please see ​https://github.com/szepeviktor/debian-server-tools/blob/master/webserver/apache-conf-available/wordpress.inc.conf#L13-L85