Why Your Gutenberg Editor Preview Looks Different (And How to Fix It)

One of the most common frustrations for WordPress users is when a page looks perfect in the Gutenberg block editor but appears broken, distorted, or completely different once published or previewed. This discrepancy between the editing experience and the final output can halt your workflow. Based on common community reports, this article explains why this happens and outlines the most effective troubleshooting steps to resolve it.

Why Does This Preview Mismatch Happen?

The Gutenberg editor operates in a controlled environment within your WordPress admin. The final published page, however, is rendered by your theme and can be affected by other plugins. A difference in appearance is almost always caused by one of the following factors:

• Plugin or Theme Conflicts: A third-party plugin or your theme might not be fully compatible with your version of WordPress or the Gutenberg editor itself, causing CSS or JavaScript to load incorrectly.
• Outdated Software: Using an outdated version of WordPress, the Gutenberg plugin (if installed separately), or a block plugin can mean you're missing crucial bug fixes and compatibility updates.
• CSS Styling Differences: The editor applies its own base styles. If your theme's stylesheet does not properly style blocks in both the editor and the front end, they will look different.
• Caching: Sometimes, your browser, a plugin, or your host is serving a cached version of the page that doesn't reflect your recent changes.

How to Troubleshoot and Fix the Issue

Follow these steps to identify and resolve the cause of the preview mismatch.

1. Conduct a Conflict Test

This is the most critical step. You need to determine if the problem is caused by your theme or another plugin.

1. Switch to a Default Theme: Temporarily switch your theme to a default WordPress theme like Twenty Twenty-Four. Clear your cache and check if the preview problem persists. If it's resolved, the issue lies with your original theme.
2. Deactivate Plugins: If the theme change didn't help, deactivate all your plugins except Gutenberg. If the problem is fixed, reactivate your plugins one by one, checking after each one, to identify the culprit.

2. Update Everything

Ensure all your software is up to date. An update often includes compatibility patches.

• Update WordPress to the latest version.
• Update all plugins, especially those that add blocks (e.g., 'Qubely – Advanced Gutenberg Blocks', 'ACF').
• Update your theme.

Note: As seen in the community threads, specific issues like the preview button publishing a post or the viewportWidth property not working were directly fixed in updates to ACF and WordPress 5.7, respectively.

3. Clear All Caches

Clear your browser cache, any caching plugin you have running, and your hosting provider's server cache (if applicable). Then, reload the page to see your changes.

4. Check for Known Issues

If a specific plugin or theme appears to be causing the problem, visit its official support forum on WordPress.org or its website. Other users may have reported the same issue, and there may be a documented fix or workaround available. For example, the 'Gutenberg' team often tracks known bugs and feature requests on their GitHub repository.

5. Understand Editor vs. Front-end Styling

It's important to know that the editor will never be a 100% perfect replica of the front end. Some themes simply apply styles differently in the two contexts. For a more accurate preview, use the "Preview in new tab" option, which shows the page as it will truly appear published. You can then use your browser's developer tools (F12) to test responsive views for mobile and tablet, which is often more accurate than the editor's device previews.

By methodically working through these steps, you can almost always pinpoint the cause of a Gutenberg preview mismatch and get your editor and published pages looking consistent again.