Unable to view Plugin Settings Page

update—
I followed the steps to reinstall the plugin:

Uninstall WP Mail SMTP option in WP Mail SMTP > Settings > Misc and then deleting the plugin.

I finally could access the settings page.

However, I encountered the problem again. I save settings with client ID and client secret, and then I got the same issue with a 502 error. In this time, I cannot see any error logs on “Debug Events”.

Hi @kogu09,

Thanks for reaching out! 502 bad gateway is a server-related issue. You can read more information from the following resources.
– https://www.wpbeginner.com/wp-tutorials/how-to-fix-the-502-bad-gateway-error-in-wordpress/
– https://kinsta.com/blog/502-bad-gateway/

Could you please report it to your hosting support and they should be able to fix it for you.

Thanks!