I have added the java system property "-Dorg.apache.tomcat.util.buf.UDecoder.ALLOW_ENCODED_SLASH=true". The log for hudson.diagnosis.ReverseProxySetupMonitor changed to:
Jul 12, 2018 2:48:42 PM FINE hudson.diagnosis.ReverseProxySetupMonitor doTest coming from https://<alias>/jenkins/manage and redirecting to https://<alias>/jenkins/administrativeMonitor/hudson.diagnosis.ReverseProxySetupMonitor/testForReverseProxySetup/https%3A%2F%2F<alias>%2Fjenkins%2Fmanage/
FYI, we're accessing our F5 load balancer via https who then accesses our server via http (SSL termination).
For testing purposes I changed the Jenkins Location URL to http://<machine name>:8080/jenkins and accessed http://<machine name>:8080/jenkins/manage and the error message was gone. This however is obviously not optimal since we want to access our application via https.
This message was sent by Atlassian JIRA (v7.10.1#710002-sha1:6efc396)
You received this message because you are subscribed to the Google Groups "Jenkins Issues" group.
To unsubscribe from this group and stop receiving emails from it, send an email to [hidden email].
For more options, visit https://groups.google.com/d/optout.