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  1. Red Hat 3scale API Management
  2. THREESCALE-11941

Requests to backend redis fails with the error "ERR max number of clients reached"

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    • Icon: Bug Bug
    • Resolution: Unresolved
    • Icon: Critical Critical
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    • 2.15.3 GA
    • Backend
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    • Workaround Exists
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      Disable async redis client by patching the APIManager CR with the following command:

      $ oc patch apimanager/${APIMANAGER_NAME} --type=merge -p '{"metadata": {"annotations": {"apps.3scale.net/disable-async": "true"}}}'

      Please note that the Horizontal Pod Autoscaler (HPA) will also be disabled as a result of this workaround.

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      Disable async redis client by patching the APIManager CR with the following command: $ oc patch apimanager/${APIMANAGER_NAME} --type=merge -p '{"metadata": {"annotations": {"apps.3scale.net/disable-async": "true"}}}' Please note that the Horizontal Pod Autoscaler (HPA) will also be disabled as a result of this workaround.
    • Important

      Customer upgraded 3scale from 2.14.2 to 2.15.3 and encountered the issue that API requests failed with the error 403 because backend-listener failed to access to backend redis with the error "ERR max number of clients reached" like:

      2025-08-29T15:14:32.916748248Z xxx.xxx.xxx.xxx - - [29/Aug/2025 15:14:20 UTC] "GET /transactions/authrep.xml?service_id=7&service_token=...&usage%5Bhits%5D=1&app_key=...&app_id=...&log%5Bcode%5D=401 " 500 "ERR max number of clients reached" 0.016502472 - "rejection_reason_header=1&limit_headers=1&no_body=1"

      This error happened not only in backend-listener but also  the following pods as well.

      • backend-listener
      • backend-worker
      • system-app (system-developer/system-provider containers)
      • system-sidekiq

      In this environment, an external Redis Sentinel (version 6.2.18) is used with async redis client and it's observed that the number of connections to redis sentinel instance in backend-listener is gradually increasing.

              Unassigned Unassigned
              rhn-support-hmiura Hiroko Miura
              Aleksandar Kostadinov, Jose Miguel Gallas Olmedo
              Joan Lledo Joan Lledo
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                Created:
                Updated: