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Support Article

Pega Connect-REST receives HTTP 504 Unknown Host error



In Pega 7.2.2, some Connect-REST calls fail with an 'HTTP Status code: 504 Unknown Host' error.

Error Messages

[WebContainer : 16] [TABTHREAD5] [RBSACPMFW:01.01.01] ( INFO xxxxxxxx|xxxxxxx|Rule-Connect-REST.PEGB-Int-Connector-CMODService-CMODSOAP-.GetCMODReport xxxxx- HTTP Status code: 504 Unknown Host [WebContainer : 16] [TABTHREAD5] [PEGBCPMFW:01.01.01] ( DEBUG xxxxxxxx|xxxxxxx|Rule-Connect-REST.PEGB-Int-Connector-CMODService-CMODSOAP-.GetCMODReport xxxxx - ------------------HTTP RESPONSE CONTENTS------------------ Response Headers: Cache-Control: no-store Content-Language: en Content-Length: 666 Content-Type: text/html Date: Via: 1.1 ZFLTRIBPRXY Response Message Data: 666 bytes received Unknown Host Description: Unable to locate the server named "xxxxxx" --- the server does not have a DNS entry. Perhaps there is a misspelling in the server name, or the server no longer exists. Double-check the name and try again.

Steps to Reproduce

Not Applicable

Root Cause

A defect or configuration issue in the operating environment.

Proxy related JVM parameters (such as http.ProxyHost and http.ProxyPort) ae set from the application code. Pega 7.2.2 (till Pega 8.1.1) does not support local proxy settings that are applicable only for individual REST Connectors. Proxy settings are global and are set at the JVM level affecting all connectors. In this case, proxy configuration is set from the application code, such that calls are routed for only one individual Connector call through the proxy. However, the settings take effect as global to the JVM. It impacts all the outgoing REST calls and requests instead of configuring the host in the endpoint URL which is routed to the proxy host.

Pega application is designed for an environment where proxy settings are set prior to node start-up and is not subject to changes while the node is running. Therefore, it is recommended to remove proxy settings that are explicitly set from the application code and configure all such proxy settings as JVM parameters to avoid inconsistencies between different Connector calls.


Make the following change to the operating environment:

Set proxy settings such as http.ProxyHost, http.ProxyPort, and http.nonProxyHosts as JVM parameters.


Published December 4, 2018 - Updated October 8, 2020

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