Getting 503 service unavailable for a particular target server, while working for others.

[sidheshwarc]

Hi Apigee Support Team,

Recently I have been facing an issue, wherein I am getting two different errors one being "503 Service Unavailable " (Refer below Image 1) and the other being "500 Internal Server Error" (Refer the below Image 2). One thing that I had observed after deep dive into this issue is, this error gets changed depending on the way we define the <HTTPTargetConnections> tag in the target endpoints section.

Following are two scenarios stated:-

1) "503 Service Unavailable "  - Image 1

The above error is thrown when the <HTTPTargetConnections> tag is defined in the following below manner (as shown in the below image)

2) "500 Internal Server Error" - Image 2

The above error is thrown when the <HTTPTargetConnections> tag is defined in the following below manner (as shown in the below image)

Please help me understand why this behaviour and also help me resolve this issue. 
Kindly let me know what else is needed from my end.

[ganadurai]

The second scenario includes the path for the target request (using the <Path> element), but for the first scenario the target URI is dependent on the URI request to Apigee endpoint. Thats the difference between the two scenarios

Check out the debug step (classic view) at sending request to the target server. This will get you more info on whats the URI hitting the target for your two scenarios.

Hope this helps.
Thanks.

[sidheshwarc]

Thanks for your response, but the thing is its not reaching the target/backend only hence the above errors. So, I need the resolution behind this, what exactly could be the root cause, why am I facing the above errors for the target that I am trying while its working fine for others.

[ganadurai]

Request from Apigee to backend (target) failure could be of various/many reasons. ...

Lets start by checking from debug screens the complete URI Apigee is trying to post the request.  compare the URIs between the working and non-working.