How to quickly locate 502 problems with Nginx

Question

On the homepage of my website, 502 will occasionally appear. There is no complicated logic. It does not necessarily appear every time, but it only happens occasionally
Is there any way to find out where this problem lies? I can't see any problems in error_log and access_log

Answer 1

50x errors are all server-side errors, don’t check in the nginx log:
(1) Go to the exception log of the framework to find it (if the exception is caught);
(2) Go to the error_log of php to find it.