Problem: If you're experiencing a 500 internal server error when accessing WordPress REST API endpoints like wp-json/wp/v2/posts with the default language parameter (?lang=ar) in a multilingual site using WPML, the issue might be due to incorrect string translations. Solution: We recommend checking the translation of specific strings in the WPML String Translation. For instance, the problematic string could be:
Delete the user's %1$s and %2$s data when the %3$s access expires.
Ensure its translation is accurate. In this case, the correct translation should be:
احذف بيانات المستخدم %1$sو %2$s عند انتهاء صلاحية الوصول %3$s.
After correcting the translation, verify that the endpoint no longer returns a 500 error.
Please note that this solution might be outdated or not applicable to your specific case. 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 the issue persists, please open a new support ticket at WPML support forum for further assistance.
