Custom Gutenberg Blocks Missing or Not Working

Custom Gutenberg blocks can enhance the WordPress editing experience by providing additional layouts, content elements, and functionality. If these blocks suddenly disappear, fail to load, or stop working correctly, the issue is usually related to plugin compatibility, outdated block libraries, caching, or JavaScript conflicts.

This guide explains the most common causes and provides step-by-step solutions to restore your custom blocks.

Common Symptoms

If you’re experiencing issues with custom blocks, you may notice one or more of the following:

• Custom blocks no longer appear in the Block Inserter.
• Existing blocks display “This block contains unexpected or invalid content.”
• Blocks appear as unsupported or unavailable.
• Blocks fail to render in the editor.
• The editor displays loading errors when using custom blocks.
• Block settings are missing from the sidebar.
• Previously created pages show broken or missing layouts.
• The frontend displays block errors or missing content.

Common Causes

Custom block issues are typically caused by one of the following:

• An outdated block plugin.
• A plugin conflict.
• Theme compatibility issues.
• JavaScript errors.
• Cached JavaScript or CSS files.
• Corrupted plugin files.
• Disabled REST API functionality.
• Changes to custom block code after a plugin update.
• Missing or corrupted WordPress core files.

Solution 1: Update Your Block Plugin

Many custom blocks are provided by plugins. If the plugin hasn’t been updated recently, it may no longer be fully compatible with the latest version of WordPress.

Update the plugin to the latest available version and test the affected blocks again.

If multiple block plugins are installed, update all of them before continuing with additional troubleshooting.

Solution 2: Verify the Plugin is Active

It may sound obvious, but custom blocks disappear immediately if the plugin providing them has been disabled.

Go to Plugins → Installed Plugins and confirm that the block plugin is active.

If the plugin was accidentally deactivated, reactivate it and reload the editor.

Solution 3: Clear All Caches

Old cached JavaScript and CSS files can prevent custom blocks from loading correctly.

Clear:

• Browser cache.
• WordPress cache.
• Server cache.
• CDN cache.
• Object cache.

After clearing the cache, perform a hard refresh and reopen the editor.

Solution 4: Check for Plugin Conflicts

If updating the block plugin doesn’t resolve the issue, another plugin may be interfering with it.

Temporarily disable all plugins except the block plugin.

If the blocks begin working again:

1. Reactivate plugins one at a time.
2. Test the editor after each activation.
3. Identify which plugin causes the conflict.

Once identified, update, replace, or remove the conflicting plugin.

Solution 5: Switch to a Default Theme

Some themes include custom JavaScript or CSS that affects Gutenberg.

Temporarily activate a default WordPress theme.

If the custom blocks start working, your theme is likely responsible.

Update the theme or contact the developer for a compatible version.

Solution 6: Check the Browser Console

JavaScript errors often prevent custom blocks from loading correctly.

To inspect errors:

1. Open the editor.
2. Press F12.
3. Select the Console tab.
4. Refresh the page.

Look for errors referencing:

• Missing JavaScript files.
• Plugin scripts.
• Block registration failures.
• REST API requests.
• React errors.

These messages can help identify the source of the problem.

Solution 7: Verify the REST API

Many Gutenberg blocks rely on the WordPress REST API to retrieve settings and content.

Visit:

https://yourdomain.com/wp-json/

If the page does not return a valid JSON response, the REST API may be blocked.

Common causes include:

• Security plugins.
• Firewall rules.
• Server configuration.
• Incorrect permalink settings.

Resolving REST API issues often restores missing blocks.

Solution 8: Reinstall the Block Plugin

Plugin files can occasionally become corrupted during an update.

To reinstall safely:

1. Export any plugin-specific settings if supported.
2. Delete the existing plugin.
3. Install the latest version.
4. Activate the plugin.
5. Test the affected blocks.

Most well-developed plugins preserve their settings during reinstallation, but it’s always a good idea to create a backup beforehand.

Solution 9: Check for Invalid Block Content

If existing pages display the message “This block contains unexpected or invalid content,” the block’s structure may have changed after an update.

In many cases, WordPress provides options to:

• Attempt Block Recovery.
• Convert the block to HTML.
• Resolve the block manually.

Before accepting any changes, compare the preview to ensure your content remains intact.

Solution 10: Restore From a Backup

If the issue began immediately after updating a plugin or making changes to your website, restoring a recent backup may be the fastest solution.

Restore:

• Website files.
• Database.
• Plugin files.

After restoring, update plugins one at a time while testing your custom blocks between updates.

Best Practices

To avoid custom block issues in the future:

• Keep your block plugins updated.
• Remove block plugins you no longer use.
• Avoid installing multiple plugins that provide similar block collections.
• Test plugin updates on a staging website before applying them to your live site.
• Keep WordPress, themes, and plugins up to date.
• Create regular backups before major updates.
• Review plugin changelogs for breaking changes before updating.

Following these best practices will help ensure your custom Gutenberg blocks remain stable and functional, reducing the risk of missing content or editor issues in the future.