- Administrator has si4t (or other custom functionality) configured, and has requirement to temporarily disable the si4t integration in the deployer-web addon.
- Administrator has removed the si4t related pipelines from the manifest.json file.
- Administrator has modified the udp-deployer-web-extension-assembly.RELEASE_NUMBER-release.json file so that the isEnabled attribute has value of false

"live": {
        "isEnabled": false,
        "configuration": {
          "gwUrl": ...
          "gwApiKey": ...
        }
  } 

- After restarting the Deployer, publishing fails with errors such as the below.

ERROR BaseHTTPSTransportConnector - Unable to execute batchRetrieve on destination: https://DEPLOYER:8443/httpupload due to: java.io.IOException. MaxRetries exceeded.
java.io.IOException: The destination is not available. Response: 502
...
ERROR [deployer-combined-service,live] 13 --- [eue)-6-thread-1] c.s.d.d.w.queue.impl.CommandQueuePoller : 
Could not process command: JSONCommand{verbs=[Content], action='TridionBootstrap', binaryIds=[tcm_0-1172066-66560.Content.zip], 
executionId='tcm:0-1172066-66560', properties={}}

Issue resolved after administrator reverted the isEnabled attribute in configuration json file to true and restarted Deployer.