wp_should_output_buffer_template_for_enhancement filter breaks custom site builder header

[Nikhil.sharma]

Hello Elementor Team,

We're experiencing an issue after Elementor v3.33.3 release that affects our site builder header functionality.

Problem: Our custom site builder header breaks on Elementor pages. After investigation, we found that Elementor disables WordPress template buffering with this code:

if ( version_compare( get_bloginfo( 'version' ),'6.9', '>=' ) ){add_filter( 'wp_should_output_buffer_template_for_enhancement', '__return_false', 1 ); }

This prevents our site builder header from rendering correctly. We've also noticed that Astra's site builder faces a similar issue with this filter, suggesting this may affect other theme/plugin builders that rely on WordPress template buffering. This appears to be a broader compatibility concern.

Our Solution: We're re-enabling buffering when our site builder header is active. However, we're concerned this might break some Elementor functionality, as we're not sure why you introduced this change in the first place.

 

[Community]

You’re running straight into a WordPress 6.9 core change and Elementor’s (very blunt) compatibility guard around it.

What that WordPress 6.9 “template enhancement buffer” is for​

WordPress 6.9 introduced an optional output buffer around template rendering (“template enhancement output buffer”) so plugins can post-process the final HTML for progressive enhancements, mainly performance-related transformations (e.g., tweaking lazy-loading, inlining, analytics injection, etc.). Core explicitly frames it as something a site can opt out of to preserve streaming responses, and warns extenders not to rely on it for critical content/functionality.

That’s the key: if your header requires that buffer to exist to render correctly, WordPress considers that an unsupported dependency for this buffering system.

Why Elementor is disabling it​

Elementor is effectively opting out of this new buffering layer by forcing:

add_filter( 'wp_should_output_buffer_template_for_enhancement', '__return_false', 1 );

…on WordPress ≥ 6.9 (as you observed). That lines up with core’s design: sites/plugins may disable buffering to keep streaming and to avoid any side effects from HTML post-processing.

• Only on frontend, not in wp-admin
• Not during Elementor editor/preview contexts
• Only when your site builder header is truly active
• Use a priority that runs after Elementor’s priority 1, so you deterministically win only when you intend to

Example pattern (conceptual):

add_filter(
  'wp_should_output_buffer_template_for_enhancement',
  function ( $should_buffer ){if ( is_admin() ){return $should_buffer;
    }
    // Avoid Elementor editor/preview if you can detect it.
    if ( defined('ELEMENTOR_VERSION') && \Elementor\Plugin::$instance->editor->is_edit_mode() ){return $should_buffer;
    }
    if ( my_builder_header_is_active_for_request() ){return true;
    }
    return $should_buffer;
  },
  20
);

Why priority
So the most future-proof direction is to make your header render via normal theme/plugin rendering pathways (e.g., template parts, wp_body_open, get_header, theme hooks) rather than assuming an output buffer exists.
If your builder currently injects the header by post-processing the final HTML, consider moving to:

• Rendering header directly in the template load flow (classic theme hooks)
• Using block/theme template parts (if applicable)
• A deterministic action hook insertion point instead of “rewrite the output”

Practical recommendation​

• Keep your override, but scope it tightly (frontend + header-active + not editor).
• Add an internal toggle to disable the override if a site reports Elementor weirdness.
• Treat this as a compatibility bug: if Elementor is disabling a core mechanism that other builders used (even if “not intended”),it’s worth raising with Elementor as a real-world regression, with a minimal reproduction.

( Note this is an AI helper response, please check the info for accuracy )