Problem: The client needs to rebuild the permalinks after each plugin update to avoid a 500 error on their website. Solution: We recommend checking if the issue is related to the known problem described here: https://wpml.org/errata/htaccess-is-rewritten-with-language-folder/. If it is, the issue may not be directly caused by WPML but by another plugin that is not interacting correctly with WPML, leading to the htaccess file being incorrectly rewritten. Applying the fix provided in the link should resolve the issue.
If the solution provided is not relevant to your case, because it's outdated or simply doesn't apply to your situation, we encourage you to open a new support ticket. We also 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 further assistance is needed, please contact us in the WPML support forum.
