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Troubleshooting Common Classic Editor Issues After WordPress Updates

43 threads Sep 7, 2025 Plugin → Classic editor

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Many WordPress users rely on the Classic Editor plugin to maintain a familiar writing experience. However, updates to the WordPress core can sometimes introduce conflicts that cause the editor to malfunction. Based on community reports, this guide outlines the most frequent problems and their solutions.

Common Symptoms and Their Causes

After a WordPress update, you might encounter one or more of the following issues with the Classic Editor:

  • Blank or Malfunctioning Toolbars: The Visual and Text mode toolbars may disappear or become unclickable.
  • JavaScript Errors: Console errors mentioning deprecated jQuery functions (e.g., jQuery.fn.live() is deprecated) can break editor functionality.
  • Publishing Problems: Clicking "Publish" or "Update" results in a 404 error or the post remains in draft.
  • Media & Embed Issues: Problems adding tags, uploading media, or embedding content from YouTube/Vimeo.
  • Browser Crashes: The editor or browser tab becomes unresponsive, especially when interacting with meta boxes.

These problems are almost always caused by one of three things: a JavaScript conflict, an outdated plugin or theme, or a server configuration issue.

Step-by-Step Troubleshooting

Follow these steps to identify and resolve the conflict.

1. Check for JavaScript Errors

The first and most crucial step is to check your browser's console for errors.

  1. Open the browser's developer tools (F12).
  2. Navigate to the "Console" tab.
  3. Reproduce the issue in the editor (e.g., click a broken button).
  4. Note any red error messages. These errors often point to the specific script causing the problem, which is vital for finding a solution.

2. Perform a Conflict Test

To determine if another plugin or your theme is causing the problem, temporarily disable all other plugins and switch to a default WordPress theme like Twenty Twenty-One.

  1. Go to Plugins → Installed Plugins.
  2. Deactivate all plugins except Classic Editor.
  3. Switch your theme to a default WordPress theme.
  4. Check if the problem persists. If it is resolved, reactivate your plugins and theme one by one to identify the culprit.

3. Install the jQuery Migrate Helper Plugin

WordPress 5.5 and later removed the older jQuery Migrate library, which many plugins and themes still depended on. This is a common source of jQuery is deprecated errors.

  1. Install and activate the Enable jQuery Migrate Helper plugin.
  2. This plugin often resolves many deprecated jQuery errors automatically, restoring functionality to the Classic Editor and other affected areas.

4. Review Server and Browser Configuration

Some issues are related to how scripts are loaded on the server or in the browser.

  • Async/Defer Scripts: Avoid adding async or defer attributes to scripts in the WordPress admin. This can break the loading order of essential files.
  • Output Compression: Errors like ob_end_flush(): failed to send buffer may relate to zlib output compression on the server. Contact your hosting provider to adjust this setting.
  • Browser Cache: Clear your browser cache and perform a hard reload (Ctrl+F5) to ensure you are loading the latest scripts.

Conclusion

While the Classic Editor plugin is maintained by its developers, compatibility issues can arise immediately following major WordPress core updates. The most effective approach is systematic troubleshooting: checking for JavaScript errors, testing for conflicts, and using the jQuery Migrate Helper plugin. For persistent issues, reviewing the support forums for specific error messages can often lead to a solution shared by other users.

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