Getting 503 error while deploying application

Question

hi
we faced a rear scenario,
we have deployed a patch from 1 environment to another,
inspection of package has not given any error, but at the time of import
it shows 503 error 'The page could not be loaded. [HTTP Code = 503] (APNX 1-4279-001)', and after some time it displayed the news patch deployed successfully.

any idea why this occurred ?

Raghuvaran Nagarajan · Answer

This is a know issue for starting from 7.x when Appian moved the applications to /design experience. 
 This error occurs when the /design front end times out waiting for a response from the server, this can be any activity like Application/patch deployment, opening appian objects. 
 The duration for the timeout depends on the lowest value of timeout configured on any of the systems/layers between the user and Appian server 
 
 User's local network or Proxy server 
 Load balancer layer (if present) 
 Webserver layer 
 Application server layer 
 
 To over come this issue, 
 
 Make sure that the timeout values in the layers are set to optimal levels (not too high as well) -- OR -- 
 Make the deployments in smaller packages 
 
 Thanks, 
 Raghu