502 Bad Gateway error for Azure Application Gateway (2024)

FAQs

How to resolve 502 Bad Gateway Error in Azure? ›

Check whether any NSG/UDR/Firewall is blocking access to the server. Check if application is running on correct port". I made sure that port 8000 is added to NSG inbound security rule, Load balancer rule and listens to port 8000 on App GW. This VM is pingable but can be accessed from other devices on the same subnet.

The client application gets an HTTP status code of 502 with the message "Bad Gateway" as a response for API calls. The HTTP status code 502 means that the client is not receiving a valid response from the backend servers that should actually fulfill the request.

Azure Application Gateway is a web traffic (OSI layer 7) load balancer that enables you to manage traffic to your web applications. Traditional load balancers operate at the transport layer (OSI layer 4 - TCP and UDP) and route traffic based on source IP address and port, to a destination IP address and port.

A 502 bad gateway message indicates that one server got an invalid response from another. In essence, you've connected with some kind of interim device (like an edge server) that should fetch all of the bits you need to load the page. Something about that process went wrong, and the message indicates the problem.

It can occur due to temporary issues, such as errors in server-side code or DNS problems. You can usually solve the issue by refreshing the page or waiting a few minutes. Even though it's a server-side error, the 502 Bad Gateway message might appear due to client-side factors like cache or DNS settings.

The time required to fix a 502 Bad Gateway error can vary significantly, ranging from a few minutes to several hours, depending on its root cause. If the issue can be resolved on the client side, such as by refreshing the browser, disabling a VPN, or clearing the cache, the problem could be fixed relatively quickly.

How do I restore my Azure Application Gateway? ›

You can go through this document for subnet requirements of Azure Application Gateway. Please let me know if you have any questions regarding the scenario. I understand query was regarding private IP but just a FYI: There's no way to restore an Application Gateway resource or its public IP after it's deleted.

In the Azure portal, find your resource and select Diagnostic settings. For Application Gateway, three logs are available: Access log. Performance log.

If access to the backend is blocked because of an NSG, UDR, or custom DNS, application gateway instances can't reach the backend pool. This issue causes probe failures, resulting in 502 errors. The NSG/UDR could be present either in the application gateway subnet or the subnet where the application VMs are deployed.

A 502 bad gateway error is an HTTP status code that indicates a communication error between two web servers. You can receive this error when visiting a website that gets an invalid response from its host server or experiences other issues, such as server overloads, network problems, and configuration issues.

This error indicates that either the bot returned an error or the request timed out. For more information about errors that your bot generates, go to the bot's dashboard within the Azure Portal and click the "Issues" link for the affected channel.

First, log in to the Azure Portal. Search for and select the Application Gateways option, which will display the list of application gateways. Navigate to the required app gateway for which you need to increase the request time-out period.

An error code 502 with BAD_GATEWAY in the message usually indicates that App Engine terminated the application because it ran out of memory. The default App Engine flexible VM only has 1GB of memory, with only 600MB available for the application container.

Hi Dr. A 502 Bad Gateway Error means the website you're connected to tried to relay information from another server and encountered an error. Try refreshing the page, clearing your cache and cookies, disabling your browser extensions, and switching your DNS server to resolve a 502 Gateway Error.