Search Engine: Elastic

Article ID: 132327, created on Mar 5, 2018, last review on Mar 13, 2018

  • Applies to:
  • Operations Automation 7.3


On a UI cluster/node based on RHEL6 OS, the UI logs /var/log/pa/pui/pui.log are growing rapidly during user activity in CCP v2, filling up with messages like:

14:20:16.084 [default task-241] ERROR c.o.a.s.booster.ejb.APSBoosterBean - Error occurred while handling HTTP request via Booster: unknown channel

You can find a great amount of session expiration statements as well:

22:10:08.995 [default task-66] DEBUG c.p.p.c.c.a.APS2ProxyServletResources - Session expired No such session
        at com.plesk.p2.cp.core.aps.APS2ProxyServlet.windowSessionFromRequest(
        at com.plesk.p2.cp.core.aps.APS2ProxyServletResources.service(

The same messages could appear on OSS Core in /var/log/pa/core.log in case APS Booster is not enabled on the UI node:

Mar  5 22:04:12.612 : DBG [aps-service:1412934 aps-service-task-157:662 pau]: c.p.p.tracer exit by exception: unknown channel: 75085084-34b7-4d12-ac67-b83c38b61ea8


CCP v2 onScreen notifications make use of the modern web-socket based protocol to deliver messages to end customers. For a RHEL6-based UI/Branding node, there is a RHEL issue related to malfunctioning mod_rewrite module that is unable to pass such requests as a proxy, reference:

mod_rewrite unable to proxy websocket URIs

The issue has no solution for RHEL6.

As a result of the issue, the onScreen notifications mechanism gets switched to long polling that results in eternal handling of browser sessions, until the user browser is closed. Such sessions generate a large amount of messages in the logs.


A permanent solution is to upgrade the Branding node(s) to RHEL7 based OS.

For all RHEL6 Branding nodes, correct the Apache configuration of all brands:

# sed -i 's/\tProxyPass "\/aps\/".*/\tProxyPass "\/ws\/" "ws:\/\/MN_IP:8080\/ws\/" disablereuse=on\n&/' brand_*.conf

Where MN_IP is the actual IP address of the Management Node.

Reload Apache service afterwards:

# apachectl graceful

IMPORTANT: the altered configuration may change any time, when a brand is re-configured in CP, so the above solution is to be re-applied again.

To be sure that the CCP v2 onScreen notifications started to work in web-socket mode, ensure the following lines appear in /var/log/pa/core.log on OSS Core while opening a CCP v2 screen:

configuring client connection with notifications channel

5356b422f65bdad1c3e9edca5d74a1ae caea8340e2d186a540518d08602aa065 e12cea1d47a3125d335d68e6d4e15e07 dd79f16c76b9dca75205ab5e9f5465ea 1941880841f714e458ae4dc3d9f3062d

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