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Fixing Common WordPress Importer Errors: Activation, Deprecation, and PHP Issues

34 threads Sep 10, 2025 Plugin → Wordpress importer

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Understanding Common WordPress Importer Errors

The WordPress Importer plugin is a powerful tool for migrating content, but users often encounter errors during activation or use. Based on community reports, the most frequent issues fall into three categories: activation failures due to redeclaration errors, deprecated function warnings, and PHP compatibility problems. This guide explains why these happen and provides the most reliable solutions.

1. Activation Fatal Errors: "Cannot redeclare" or "Cannot declare class"

Why it happens: These errors occur when the plugin tries to load the same function or class twice. Common causes include:

  • The plugin being installed as both a regular plugin AND a Must-Use (MU) plugin simultaneously.
  • Another plugin or theme including a conflicting version of the same class (like WXR_Parser).
  • A corrupted or incomplete plugin installation.

Solutions:

  1. Check for Duplicate Installations: Connect to your site via FTP or your host's file manager. Look for the wordpress-importer folder in both /wp-content/plugins/ and /wp-content/mu-plugins/. If it exists in both, delete the folder from the mu-plugins directory.
  2. Conflict Test: Deactivate all other plugins and switch to a default theme (like Twenty Twenty-One). Try activating the WordPress Importer again. If it works, reactivate your plugins one by one to find the conflict.
  3. Reinstall Cleanly: Delete the existing wordpress-importer folder completely. Then, install a fresh copy directly from the WordPress plugin repository.

2. Deprecated Function Warnings (e.g., wp_get_http)

Why it happens: WordPress continuously evolves, and older functions are eventually deprecated and replaced with newer methods. The wp_get_http() function was replaced by the WP_Http class in WordPress 4.4. While these notices may not break the import, they indicate the plugin's code needs updating.

Solutions:

  1. Update the Plugin: The WordPress Importer team released version 0.6.4 to address many of these deprecation notices. Ensure you are using the latest available version of the plugin.
  2. Understand the Limits: If you are on the latest version and still see a deprecation notice (especially on newer PHP versions), it may be a known issue that has not been patched yet. You can often safely ignore these notices if the import completes successfully, as they are warnings, not errors. For a production site, consider disabling WP_DEBUG mode to hide these notices from users.

3. PHP Compatibility Issues (PHP 7, 8, and 8.3)

Why it happens: Newer versions of PHP introduce changes that break compatibility with older code. For example, PHP 7 deprecated constructors with the same name as their class, and PHP 8.3 deprecated passing null to certain string parameters.

Solutions:

  1. Check the Version: Community reports indicate that version 0.6.4 of the importer included fixes for PHP 7 compatibility. Again, verify you have the most recent version installed.
  2. PHP 8.3 Warnings: Warnings about undefined array keys and passing null to preg_match() are known issues with the plugin's parser. As these are typically warnings and not fatal errors, the import may still function. The best course of action is to monitor the plugin's official development channel for a future update that addresses PHP 8.x compatibility specifically.
  3. Manual Code Edits (Advanced): Some community members have shared modified versions of the plugin's code to fix specific issues. Warning: Editing plugin files directly is not recommended, as your changes will be overwritten the next time the plugin is updated. If you must do this, always create a full backup first and note that you are proceeding at your own risk.

Summary: Best Practices for a Smooth Import

  • Always Update: Use the latest version of the WordPress Importer from the official repository.
  • Test in a Safe Environment: Perform imports on a staging or development site first, not directly on a live production site.
  • Simplify for Troubleshooting: Deactivate other plugins and use a default theme when troubleshooting import issues to rule out conflicts.
  • Check File Locations: Ensure the plugin is only installed once and in the correct /plugins/ directory.

By following these steps, you can resolve the majority of common errors encountered with the WordPress Importer plugin.

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