Iis Error Code 502
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502 Bad Gateway Meaning
Troubleshooter: IIS Failed Request Tracing Network Monitor Winhttp Tracing This material is provided for informational purposes only. Microsoft makes no 502 bad gateway fix warranties, express or implied. HTTP 502 - Overview When working with IIS Application Request Routing (ARR) deployments, one of the errors that you may see is "HTTP 502 - Bad Gateway". The 502.3 error means please explain this 502 bad gateway error that - while acting as a proxy - ARR was unable to complete the request to the upstream server and send a response back to the client. This can happen for multiple reasons - for example: failure to connect to the server, no response from the server, or the server took too long to respond (time out). If you are able to reproduce the error by browsing the web
504 Bad Gateway
farm from the controller, and detailed errors are enabled on the server, you may see an error similar to the following: Figure 1 (Click image to expand) The root cause of the error will determine the actions you should take to resolve the issue. 502.3 Timeout Errors The error code in the screenshot above is significant because it contains the return code from WinHTTP, which is what ARR uses to proxy the request and identifies the reason for the failure. You can decode the error code with a tool like err.exe. In this example, the error code maps to ERROR_WINHTTP_TIMEOUT. You can also find this information in the IIS logs for the associated website on the ARR controller. The following is an excerpt from the IIS log entry for the 502.3 error, with most of the fields trimmed for readability: sc-status sc-substatus sc-win32-status time-taken 502 3 12002 29889 The win32 status 12002 maps to the same ERROR_WINHTTP_TIMEOUT error reported in the error page. What exactly timed-out? We investigate this a bit further by enabling Failed Request Tracing on the IIS server. The first thing we can see in the failed request trace log is where the request was sent to in the ARR_SERVER_ROUTED event. Th
This server received an invalid response from an upstream server it accessed to fulfil the request. This usually does not mean that the upstream server is down (no response to the gateway/proxy), but rather 502 proxy error that the upstream server and the gateway/proxy do not agree on the protocol for exchanging 502 bad gateway nginx/1.4.6 (ubuntu) data. Given that Internet protocols are quite clear, it often means that one or both machines have been incorrectly or incompletely programmed. Fixing
The Proxy Server Received An Invalid Response From An Upstream Server.
502 errors - general This problem is due to poor IP communication between back-end computers, possibly including the Web server at the site you are trying to visit. Before analysing this problem, you should clear your browser cache https://www.iis.net/learn/extensions/troubleshooting-application-request-routing/troubleshooting-502-errors-in-arr completely. If you are surfing the Web and see this problem for all Web sites you try to visit, then either 1) your ISP has a major equipment failure/overload or 2) there is something wrong with your internal Internet connection e.g. your firewall is not functioning correctly. In the first case, only your ISP can help you. In the second case, you need to fix whatever it is that is preventing you reaching the Internet. If you http://www.checkupdown.com/status/E502.html get this problem for only some of the Web sites you try to visit then it is likely to be a problem at those sites i.e. one of their pieces of equipment is failing/overloaded. Contact the people at those sites. Fixing 502 errors - CheckUpDown Our service monitors your site for HTTP errors like 502. Use of proxies and caching is increasing on the Web. Our CheckUpDown robot will always try to "drill through" to the real computer that actually hosts the Web site, but we do not have complete control over where our HTTP request actually ends up. If only one link in the chain of computers dealing with our HTTP request is broken, then an error such as 502 can easily occur. Please contact us (email preferred) whenever you encounter 502 errors - there is nothing you can do to sort them out. We then have to liaise with your ISP and the vendor of the Web server software so that they can review the flow of IP data traffic between various computers under their control. 502 errors in the HTTP cycle Any client (e.g. your Web browser or our CheckUpDown robot) goes through the following cycle when it communicates with the Web server: Obtain an IP address from the IP name of the site (the site URL without the leading 'http://'). This lookup (conversio
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