Out of sync error

Hi,

I have created an application in Vaadin, it works locally but on a remote host it gets Out of sync errors so often that it is unusable.

In logs you can see:

error on my serwer (com.vaadin.terminal.gwt.server.AbstractCommunicationManager handleVariableBurst
WARNING: Warning: Ignoring variable change for non-existent component, VAR_PID=PID217)

What can I do?

Thanks in advance,
Etam.

Just some guesses as with just that description it is hard to track down.

Basically, you get that error when something changes the UI on the server side (or client side) but the changes were not sent updated on the client side (or server side). So it comes from your code, somewhere. Some things to check :

Are you by any chance using any static variables ? See here for how not to use them (as they are not shared nicely).
Are you doing background changes (ie. other threads) to update the UI ? If yes, you need to synchronize on the current user's application instance any change.
Have you added multiple tabs support (should not be the reason, but can help), if no see here.

Do you have a load balancer, a cluster, using app engine or anything between your user and the server which would cause the session state to be damaged on the way ?