Problem: The client is experiencing errors when attempting to add translations to a page or a post after migrating their website to a production domain. The debug log file shows the following error:
PHP Fatal error: Uncaught Error: Call to undefined function mb_ereg_replace_callback() in ....../wp-content/plugins/sitepress-multilingual-cms/classes/xliff/class-wpml-tm-validate-html.php:124
Solution: We have identified that the 'Multibyte String' PHP extension is not enabled on the client's server, which is necessary for WPML to function correctly. We recommend contacting the hosting provider to enable this extension. For more details on the 'Multibyte String' PHP extension, please visit WPML's minimum requirements and the PHP manual.
If this solution does not apply to your case, or if it is outdated, we highly recommend checking related known issues at https://wpml.org/known-issues/, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. If you still need assistance, please open a new support ticket in our forum.
