Health checks returning 502 and 403 errors


We are using Haproxy 2.5 and have a group of backend servers that all of sudden started to return layer7 502 and 403 errors in their haproxy health checks although direct access to the servers proves that they are accessible and responsive.
I do not know where to start looking. So, any help with what could be the problem and how to solve it is much appreciated.

Best Regards.

You should start looking at your backend servers log files.