Polling from a slave does not seem to work anymore because of a SecurityException (Probably JEP-200).

...

Polling remotely on BuildSlave

Trying to monitor the folder '//server/builds/libs'
[ERROR] - Polling error...
[ERROR] - Error message: java.io.IOException: remote file operation failed: C:\jenkins at hudson.remoting.Channel@ffce84:JNLP4-connect connection from atfkjb01/10.10.250.142:3413: java.io.IOException: Failed to deserialize response to UserRequest:org.jenkinsci.plugins.fstrigger.triggers.FolderContentTrigger$1@57dea97f: java.lang.SecurityException: Rejected: org.jenkinsci.lib.xtrigger.AbstractTrigger; see https://jenkins.io/redirect/class-filter/
[ERROR] - Error cause: remote file operation failed: C:\jenkins at hudson.remoting.Channel@ffce84:JNLP4-connect connection from atfkjb01/10.10.250.142:3413: java.io.IOException: Failed to deserialize response to UserRequest:org.jenkinsci.plugins.fstrigger.triggers.FolderContentTrigger$1@57dea97f: java.lang.SecurityException: Rejected: org.jenkinsci.lib.xtrigger.AbstractTrigger; see https://jenkins.io/redirect/class-filter/