As shown on [1], the logback build on the Jenkins server on cloudbees is unstable. The failures are probably due to timeout issue. I'll work on ch.qos.logback.core.FileAppenderResilienceTest.smoke ch.qos.logback.core.recovery.ResilientOutputStreamTest.verifyRecuperationAfterFailure ch.qos.logback.core.spi.AppenderAttachableImplLockTest.detachAppenderBoom Carl, could you please have a look at ch.qos.logback.core.net.SocketConnectorBaseTest.testConnect ? You should be able to logon at https://grandcentral.cloudbees.com/ click on JenkinsCI (top right) and launch builds interactively. (You need to click on the login link in Jenkins located on the top right corner). Cheers, -- Ceki [1] https://logback.ci.cloudbees.com/job/logback/12/testReport/