Due to Fresns account center (including registration and login features) being implemented as an extendable plugin, it allows users to flexibly swap with other plugins.

Since accessing extension plugins involves transmitting "access token" information via URL, these URLs can be very long, requiring web runtime environments to support long query strings. If the configuration does not support this, a 502 error may occur.

In Nginx, handling long query strings or large request headers typically involves configuring fastcgi parameters to ensure that Nginx can properly communicate with backend FastCGI servers (like PHP-FPM).

If your web environment was set up with an unoptimized default configuration, you might experience 502 errors.

My Nginx configuration is as follows:

fastcgi_buffer_size 64k;
fastcgi_buffers 4 64k;
fastcgi_busy_buffers_size 128k;