"Communication Problem"s after SSL

Hello all,

We are getting significant amount of “Communication Problem” messages after enabling SSL on the server. Is there any tuning point to get rid of this disturbances?

Vaadin Version: 6.4.9
App Server: Glassfish 3.0.1

We are also experiencing too many communication problem messages.

Could there be any other cause than actual lost of connection?

Sadly, I had to start porting my application to GWT/GXT platform due to this problem.

A little more information would be useful. Does the communication errors occur seemingly at random? After being idle for a while? Any special action that triggers them? I don’t see why it would be related to SSL. One option is also that there really is some other error (like session timeout) which is for some reason shown as a communication error because of SSL.


First of all thank you for your response. The communication problem error definitely occurs randomly and independent from OS and Browsers. Tests failed on different OS x Browser variations like Ubuntu - Chrome and Windows XP - IE8. We can not define a pattern to see this error continuously. We changed client server communication pattern from pull to push with Vaadin Plugins. This action reduced errors but not ended.

To give an example, sometimes this problem can occur just after user logged in or send a request to server, without any idle time.


sometimes the error message contains following text:

Proxy Error, the proxy server received an invalid response from an upstream server.

More often, shorter communication error message is shown, although other sites (and therefore internet connection) seems to work.

We don’t have too detailed information on usage patterns, unfortunately. But it seems random.

With proxy error message, session timeout was not the case. What could cause proxy error?


So it is http error code 502? Hard to say what could cause it. Once it happens you could check both proxy servers and app servers logs for any hints at all.

If it is some sort of temporary problem (like network issue between proxy and app server), we could probably modify the Vaadin client side a bit to be more tolerable on those. We already have a special handling for 503’s to cope better with google app engine. If it happens we just repost the previous message. Adding a 502 to the same switch case clausal might resolve the issue. If the error happens before the message from the client is handled this would be perfectly safe, otherwise it might be safer to reload the whole page.