After the upgrade all our Windows slaves could not be reached:

C:\jenkins>java -jar slave.jar -jnlpUrl http://bambpmsauto.eur.ad.sag:8080/compu
ter/vmbam04.eur.ad.sag/slave-agent.jnlp
Failing to obtain http://bambpmsauto.eur.ad.sag:8080/computer/vmbam04.eur.ad.sag
/slave-agent.jnlp
java.io.IOException: Failed to load http://bambpmsauto.eur.ad.sag:8080/computer/
vmbam04.eur.ad.sag/slave-agent.jnlp: 403 Forbidden
at hudson.remoting.Launcher.parseJnlpArguments(Launcher.java:228)
at hudson.remoting.Launcher.run(Launcher.java:190)
at hudson.remoting.Launcher.main(Launcher.java:166)
Waiting 10 seconds before retry
Failing to obtain http://bambpmsauto.eur.ad.sag:8080/computer/vmbam04.eur.ad.sag
/slave-agent.jnlp

I also tried headless slave:

CouldNotLoadArgumentException[ Could not load file/URL specified: http://bambpmsauto.eur.ad.sag:8080/computer/vmbam04.eur.ad.sag/slave-agent.jnlp]
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

java.io.IOException: Server returned HTTP response code: 403 for URL: http://bambpmsauto.eur.ad.sag:8080/computer/vmbam04.eur.ad.sag/slave-agent.jnlp
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at com.sun.deploy.net.HttpUtils.followRedirects(Unknown Source)
at com.sun.deploy.net.BasicHttpRequest.doRequest(Unknown Source)
at com.sun.deploy.net.BasicHttpRequest.doRequest(Unknown Source)
at com.sun.deploy.net.BasicHttpRequest.doGetRequest(Unknown Source)
at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(Unknown Source)
at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(Unknown Source)
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

This must be a regression of some kind because all the slaves were fine before the upgrade of the version (we were on 1.497 as 1.498 had similar problems)