Problem: The client is experiencing a critical error when attempting to use the advanced editor for translating a page from English to French. The error message indicates a missing site key and issues with the WPML Translation Editor, potentially due to conflicts with hidden builder metadata or cached layout data from Visual Composer. Solution: We recommend creating a new page and manually copying the content from the problematic page to the new one. This approach often helps clear out any residual builder metadata that might be causing the issue. If this solution does not resolve the problem or if it seems outdated or irrelevant to your current setup, please check the related known issues, verify the version of the permanent fix, and confirm that you have installed the latest versions of themes and plugins. If issues persist, we highly recommend opening a new support ticket for further assistance.