What does this networking error mean for users and website owners?
If you have ever visited a website only to see an error message ‘502 Bad Gateway’ and wondered what it means, then read on.
It’s not really anything to do with your browser or internet connection, rather there is something wrong at the other end, i.e. there is a problem with the website itself.
When you do see a 502 Bad Gateway error, this is an HTTP status code. It means that a server at the other end (and we don’t always mean a web server), is acting as a gateway or proxy and has accepted an invalid response from an upstream (or origin) server.
As said earlier, there is no problem with your desktop, laptop, or smartphone, nor is there an issue with your browser or operating system.
There is a whole array of error messages from 500 to 599, all of these are when a server fails to do something when it tries to fulfill a request. It doesn’t mean that a server has gone down. Instead, the upstream server and the gateway server can’t agree on a protocol for exchanging data.
As internet protocols are generally clear, this means that one or both servers have been wrongly or incompletely configured.
Reasons for a 502 Bad Gateway response
There many reasons why a user will observe a 502 Bad Gateway response.
Server overload – A server can crash if it has exhausted its memory, due to a multitude of visitors on site or a DDOS attack.
Firewall blocks a request – A firewall may block communications between an edge server and upstream server. Some DDoS protection systems can over-react and block requests from a content delivery system.
Faulty programming – sometimes an error in a website’s code may mean that requests cannot be answered correctly, prompting this error to show up.
Network errors – DNS issues, routing problems, and ISP related issues can also lead to a 502 Bad Gateway error.
Server software timeouts – This error can also occur when a web server takes more time to complete and a caching tool reaches its timeout values that time. Slow queries can also cause this problem too.
How to fix a 502 Bad Gateway error
Usually, these errors will go away by themselves and refresh a web browser page may be all that is needed to get the page you were looking for. If this happens, then the problem was a temporarily overloaded server.
Should it continue to happen, they’re using a web service such as Down for everyone or just me? will tell you if the problem is more widespread. Use of a third-party proxy such as Hide My Ass can sometimes eliminate problems with a particular ISP (maybe the ISP blocks access to a particular website).
If this error happens regularly, you will need to investigate it in order to find a solution. Examining web server logs at the time of the error occurring will be a good place to start. If you are the owner of the website, you can check your FQDN (fully qualified domain name) is correctly resolving. You can also check a server is reachable via a ping text or traceroute.