Problem: After migrating a multi-lingual site to a new production server, the backend became very slow, primarily due to frequent API calls made by the WPML Multilingual CMS plugin, resulting in '426 Upgrade Required' errors. Solution: First, ensure that all WPML plugins are updated to their latest versions. Next, within the WPML settings, switch the translation editor as this might resolve the issue temporarily. Additionally, check WPML logs for repeated API requests and review server resource usage to identify any loops or redundant external calls. If these steps do not alleviate the problem, it may be due to a bug that our developers are currently investigating. In this case, switching the translation editor as per the instructions in WPML → Settings should serve as a temporary workaround.
Please note that this solution might become outdated or may not apply to your specific situation. If the issue persists, we highly recommend checking related known issues, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. If necessary, please do not hesitate to open a new support ticket.
