Find Legacy Blocks Preventing the New Block Editor Experience

WordPress 6.3 introduced a new iframe-based block editor. But here’s the catch: if you have even one block using API version 1 or 2, WordPress falls back to the old editor layout. If you’re missing out on the new editor experience and want to figure out why, this console command will show you exactly which blocks are holding you back.

Benefits of the iframe Block Editor

The iframe-based editor completely isolates your content from WordPress admin styles, creating a true WYSIWYG experience where viewport units like vw and vh work correctly, media queries behave natively, and front-end styles drop into the editor with minimal adjustments. Admin and content styles no longer interfere with each other, and since WordPress handles asset loading through enqueue_block_assets, this makes the transition smooth for developers while delivering a cleaner, more accurate editing experience.

On to the Code!

Open your browser’s console (F12 or right-click → Inspect → Console) while editing any page or post in the block editor, then paste this and click enter. You should get a list in your console showing the block title, name, and API version for anything that isn’t v3 yet.

wp.blocks.getBlockTypes().filter(b => b.apiVersion < 3).forEach(b => console.log(`${b.title} (${b.name}) - API v${b.apiVersion}`))

wp.blocks.getBlockTypes().filter(b => b.apiVersion < 3).forEach(b => console.log(`${b.title} (${b.name}) - API v${b.apiVersion}`))

How It Works

The snippet uses WordPress’s built-in wp.blocks.getBlockTypes() function to grab all registered blocks, then filters them to find any using an API version less than 3. It returns a list showing each block’s name and its current API version.

Once you identify the legacy blocks, you can either unregister blocks you don’t need, or reach out to the plugin developer to see if they have an updated version available.