[robelsust]

Description

Trac Ticket: https://core.trac.wordpress.org/ticket/66354

When a browser extension (such as React Developer Tools or Vue DevTools) or missing asset requests a .map sourcemap file (e.g. /wp-admin/installHook.js.map) or a missing asset within the administration or includes directory, server rewrite rules pass the request to index.php.

Because no post or page matches the path, WordPress flags is_404() = true and invokes the full 404 template loader. In block themes, this renders the theme canvas and executes render_block_core_template_part() for header and footer template parts, executing database queries, running transient caches, and returning invalid HTML for what should be a lightweight JSON sourcemap or asset 404.

Changes

• Adds wp_short_circuit_404_assets(): bool in wp-includes/canonical.php.
• Hooks wp_short_circuit_404_assets to template_redirect at priority 1010 in wp-includes/default-filters.php (running immediately after wp_redirect_admin_locations).
• Immediately terminates 404 requests targeting .map files or paths inside admin_url() / includes_url() with a 404 status header and nocache headers.
• Adds the wp_short_circuit_404_assets filter to allow plugins to customize or override the short-circuit behavior.
• Adds dedicated unit tests in tests/phpunit/tests/canonical/shortCircuit404Assets.php.

Props @therssoftware, brumack

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Props therssoftware.

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