Communication Problem - Invalid Status Code 0

Can someone explain/clarify what causes this error: “Communication Problem - Invalid Status Code 0” ?

I’m trying to figure out if this is something with my code, the server on which the app is hosted, or what.

Most of the posts on this topic seem to have been about having a custom message when the error occurs, but they don’t address how to resolve this issue.

Users of my application are routinely “kicked off” the system due to this problem. I don’t see any errors in the server logs.

Any help would be appreciated. Thank you.

Do you have any threads in background ?

Yes. My UI has listeners and at times threads that are processing data, updating a progress bar, and generating a report.

If you are updating component or container state without synchronizing on application, you may have troubles.
I would recommend you to only do such updates into event listeners (progress bar, refresher, …) as it is easy to miss a synchronize and break the UI state.

We are seeing this error from time to time. I updated the ApplicationConnection to log stuff back to our server via an error logging jsp.

What’s interesting is that there is only 1 header “User: Unknown”
Does this mean anything to anybody?

We aren’t specifically spawning any threads. Although we do use the TPTApplication.
Maybe some of it’s lazy loading stuff is the culprit?
Also, we don’t really see this problem in our test environment. Only production.
The main difference is that production is behind a load balancer.

We have considered introducing a retry if we get the status code 0/empty response.


We have the same problem, but only Touchkit an iOS.
We do not do things in spawned threads, but we use the refresher add-on.
Any news about this problem?