Background of the issue:
I am trying to resolve a conflict between WordPress 6.5.3 and Themeco Pro Theme 6.4.21. I have tested all plugins, and even with only WPML active, we are getting bad gateway errors and are unable to navigate the back end of the site. This issue is critical as we have had no issues with WPML for years, and it is a critical part of the website. Here is the link to the page where the issue can be seen when logged in: hidden link
Symptoms:
We are experiencing bad gateway errors and are unable to navigate the back end of the site. Sometimes we couldn't log in at all, and other times it would log in but only show the home page and it was stuck.
Questions:
What could be causing the bad gateway errors with WPML active?
How can I resolve the navigation issues in the back end of the site?
Deactivating has to be done via SFTP, physically moving the plugin folder for WPML Multilingual CMS to a temp location.
When WPML Multilingual CMS is activated in any way, I get a "Bad Gateway" error and can't get to the debug information or even the main WordPress Dashboard.
FYI: WPML String Translation can be activated alone without breaking the website.
WPML Multilingual CMS cannot be activated at all, even with the WPML String Translation deactivated.
Could you please try the following steps to see if it helps?
1) Backup your website.
2) Temporarily deactivate all plugins.
3) Switch to any default theme.
4) Download fresh WPML plugins from your wpml.org account.
5) Activate WPML plugins.
6) If everything is okay, activate your previous theme.
7) Then, activate the remaining plugins (you can activate them in small groups).