PHP Fatal error: Uncaught Error: Call to undefined function wp_kses_normalize_entities() in wordpress

wp_kses_normalize_entities() is a WordPress core function that is responsible for normalizing entities in user-submitted content. It ensures that HTML entities are properly formatted and conform to standard specifications. This function is commonly used to sanitize and filter user input to prevent potential security vulnerabilities, such as cross-site scripting (XSS) attacks.

The wp_kses_normalize_entities() function is located in the wp-includes/kses.php file within your WordPress installation. It is an essential part of the WordPress core and is called by various functions and processes to sanitize content and ensure its integrity.

When encountering the error message about an undefined wp_kses_normalize_entities() function, it suggests that the function is missing or not properly defined in your installation. This can occur due to various reasons, such as incomplete or corrupted core files, compatibility issues, conflicts with plugins or themes, or modifications made to the core files.

To address this issue, the steps mentioned in the previous response provide a systematic approach to troubleshooting the problem and resolving the error. By verifying the core files, checking PHP version compatibility, disabling plugins and switching themes, and performing a fresh installation if needed, you can resolve the undefined function error and ensure the proper functioning of wp_kses_normalize_entities() within your WordPress installation.

The error message you’re encountering indicates that the function wp_kses_normalize_entities() is undefined or missing in your new WordPress installation. This function is part of the WordPress core and is responsible for normalizing entities in user-submitted content.

To address this issue, here are a few steps you can take:

1. Verify WordPress core files: Make sure that all the WordPress core files are correctly installed in your new WordPress installation. It’s possible that the installation might be incomplete or some files may have been corrupted during the process. You can try re-uploading the core WordPress files to ensure they are intact.
2. Check PHP version compatibility: Ensure that your PHP version meets the minimum requirements for the WordPress version you are using. Older PHP versions may not support certain WordPress functions. Check the official WordPress documentation for the recommended PHP version.
3. Disable plugins and switch to a default theme: Temporarily deactivate all plugins and switch to a default WordPress theme (such as Twenty Twenty-One). This will help identify if the issue is caused by a plugin or theme conflict. If the error disappears after deactivating plugins or switching themes, reactivate them one by one to identify the specific plugin or theme causing the problem.
4. Verify file integrity: Check if the wp-includes/functions.php file is intact in your installation. This file contains the definition of the wp_kses_normalize_entities() function. Make sure the file is present and has not been modified or corrupted.
5. Fresh WordPress installation: If the issue persists and none of the above steps help, consider performing a fresh installation of WordPress. Delete the current installation and reinstall WordPress from scratch. This will ensure that all necessary files are properly installed.

If the problem still persists after following these steps, it may be worth reaching out to the WordPress community forums or the official WordPress support for further assistance. Provide them with the specific error message and any relevant details about your installation to receive more targeted support.