I recently updated some older agent nodes to use the latest WinSW release (2.2.0, at present) and thought I'd switch to the WinSW.NET4.exe version, as it does not require the additional jenkins-slave.exe.config file specifying this particular runtime (vs. the default of .NET 2). The agent service installed and started fine, but the Jenkins master then attempted to auto-upgrade the jenkins-slave.exe on the agent, as shown by the "Scheduled overwrite of jenkins-slave.exe on the next service startup" message in the agent log (from https://github.com/jenkinsci/windows-slave-installer-module/blob/master/src/main/java/org/jenkinsci/modules/windows_slave_installer/SlaveExeUpdater.java#L99). Sure enough, the .NET 4 version of jenkins-slave.exe I'd put onto my agents got replaced with a .NET 2 version from the Jenkins master, and then the agent service wouldn't start because I lacked a jenkins-slave.exe.config file there.

I realize that the auto-update can be disabled via the org.jenkinsci.modules.windows_slave_installer.disableAutoUpdate setting on the master, but could we have the Jenkins master use the .NET 4 version of WinSW instead, so this isn't necessary?