Upgrading to Jenkins 2.0 causes ha health check to fail

Article ID:115000462428
1 minute readKnowledge base


  • Upgrading to Jenkins 2.0 with HA (active/passive) caused the following error:

WARNING	o.e.jetty.util.log.JavaUtilLog#warn: badMessage: 400 Bad Host header for HttpChannelOverHttp@123456{r=0,c=false,a=IDLE,uri=/ha/health-check}


  • CloudBees Jenkins Enterprise

  • Jenkins LTS

  • High Availability Plugin


In Jenkins 2.7.19, Jetty was upgraded from 8.1 to 9.2 which removes AJP functionality, and also requires that if the HOST: field is used it can not be empty.

Example of invalid string for health check:

GET /ha/health-check HTTP/1.1\r\nHOST: \r\nConnection: Close\r\n\r\n

Example of good string for health check:

GET /ha/health-check HTTP/1.1\r\nHOST:null \r\nConnection: Close\r\n\r\n

The issue is tracked as JENKINS-40693

Tested product/plugin versions

  • CloudBees Jenkins Platform v/