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Troubleshooting Common WordPress Importer Errors: 404s, 500s, and Failed Uploads

32 threads Sep 9, 2025 Plugin → Wordpress importer

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Many WordPress users rely on the WordPress Importer plugin to migrate content between sites. However, the import process can sometimes fail with confusing errors. Based on community reports, this guide covers the most common WordPress Importer issues and how to resolve them.

Common Error Messages and Their Causes

The following errors are frequently reported by users attempting to import WordPress eXtended RSS (WXR) files:

  • 404 Page Not Found (e.g., on wp-admin/admin.php?import=wordpress&step=2)
  • 500 Internal Server Error or "The site is experiencing technical difficulties"
  • "The link you followed has expired."
  • 403 Forbidden errors during import
  • Fatal PHP errors mentioning WP_Error or WP_Import class not found
  • Parser errors related to invalid WXR file structure

These errors are rarely due to a single cause. They often stem from a combination of server configuration, file upload limits, plugin conflicts, or a corrupted export file.

Step-by-Step Troubleshooting Guide

If your import is failing, work through these solutions in order.

1. Check Server Requirements and Increase Limits

Many import failures, especially those resulting in 500 errors or blank pages, are caused by server resource limits.

  • PHP Requirements: Ensure the php-xml module is installed and active on your server. This is a common missing requirement that will prevent the importer from parsing XML files.
  • Increase PHP Limits: Temporarily increase your PHP memory limit, maximum execution time (max_execution_time), and maximum upload file size (upload_max_filesize and post_max_size). An 8M file may require settings much larger than 128M to process all the associated data.

2. Verify the WXR Export File

The problem might be with the file you are trying to import.

  • Re-export: Try creating a new export file from your source WordPress site. Ensure the export process completes without errors.
  • Check File Integrity: If you see parser errors mentioning "premature end of data" or "CData section not finished," your WXR file is likely corrupted or incomplete. A re-export usually fixes this.
  • Reduce File Size: For very large sites, try exporting content in smaller chunks (e.g., only posts from a specific date range) instead of one giant file.

3. Address Permission and Security Conflicts

403 errors and issues where files cannot be moved often point to permission problems.

  • File Permissions: Check that your WordPress uploads directory has the correct write permissions so the importer can store the uploaded file.
  • Security Software: Temporarily disable any server-level firewalls (e.g., ModSecurity) or WordPress security plugins. These can sometimes incorrectly block the importer's AJAX requests, causing a 403 or 404 error.

4. Resolve Plugin and Theme Conflicts

A conflict with another plugin or your theme is a common cause of fatal errors.

  • Deactivate all plugins except for WordPress Importer.
  • Switch to a default WordPress theme like Twenty Twenty-One.
  • Attempt the import again. If it works, reactivate your plugins and theme one by one to identify the culprit.

5. Enable Debugging for Specific Errors

To get a clearer error message instead of a generic 500 or white screen, enable WordPress debugging. Add the following lines to your wp-config.php file:

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true ); // Logs errors to wp-content/debug.log
define( 'WP_DEBUG_DISPLAY', false ); // Hides errors from the screen

After attempting the failed import, check the wp-content/debug.log file for specific error messages that can point to the exact line of code causing the problem.

When All Else Fails

If you continue to experience issues, consider these alternatives:

  • The WordPress Importer plugin can sometimes struggle with major core version differences. Try using a version of WordPress closer to the source site for the import, then upgrading afterwards.
  • Some hosting providers offer their own migration tools that can be more reliable for moving content.
  • The community-maintained WordPress Importer project on GitHub may have a more recent version with fixes for specific issues.

Remember, the 'WordPress Importer' team suggests that successful importing often depends on a correct server environment and a valid export file. By methodically working through these steps, you can identify and overcome the most common obstacles.

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