500 Errors from VS After the upgrade to version 22.1.6.

Products

• VMware Avi Load Balancer

Issue/Introduction

 

• VS logs display the error "server connection setup failed".

• On client end below error would be displayed.

• After the server-side connection is closed, if the client sends a new request on the same port before the connection is fully cleared, the new connection attempt fails, ultimately resulting in a 500 error on the frontend.

 

Cause

 

• Starting from version 22.1.6, the "Preserve Client Port" feature will be enabled by default if "Preserve Client IP" is enabled in the Virtual Service application profile. As a result, when the client sends a new request using the same port, if the last connection cleanup process on the front-end not done due to the time_wait setting on the TCP profile (default is 2000ms) then the new connection attempt fails, ultimately resulting in a 500 error on the frontend. This delay in cleaning up the connection can prevent the client from establishing a new connection with the reused port, as the previous connection still exists and has not yet been fully cleared.

Resolution

Permanent Fix:

Disable the preserve_client_port on the application profile via shell.

>Configure applicationprofile HTTP-security
 >no preserve_client_port
 >save 

Or 

Enable Ignore Time Wait on the TCP proxy profile.