Probably the one where we had an error, because the service from a thirdparty we needed to install used a fourthparty service that was behind a proxy. Due of internal reasons we needed to use our own tomcat instead of the standard tomcat. We made a meeting because we didn't found out at that point that the problem was the firewall that dropped the packages from the application. We replayed it to them (at that point it was in my musclememory) and after a month i got the idea to use tcpdump to see if the server is calling another webservice, which was denied by the developers.