Natron hangs with strange error


Hi everyone, we use natron with denoiser. It reads 2 images and produce one. That works well. But sometimes the image is written and natron does not exit. If I restart natron with exactly the same input it works fine. We start natron from console (this are servers without GUI). I don’t know it this may be an issue, sometimes we start more then one natron process (another completely different task). I did some tests starting many processes in parallel but it works fine. For me it looks like some random issue. Could you explain me what is IPC_COM? Is it a pipe?
Here is the output:

[2018-03-19 16:27:52] Error while loading OpenGL: X11: Failed to open display
[2018-03-19 16:27:52] OpenGL rendering is disabled.
[2018-03-19 16:27:52] Restoring the image cache…
[2018-03-19 16:27:52] Loading plugin cache…
[2018-03-19 16:27:52] Info: script not loaded (this is not an error)
[2018-03-19 16:27:52] Loading PyPlugs…
[2018-03-19 16:27:52] Loading project: FI_63790.ntp
[2018-03-19 16:27:52] Write1 ==> Rendering started
[2018-03-19 16:27:54] Write1 ==> Frame: 2, Progress: 100.0%, 0.6 Fps, Time Remaining: 0 second
[2018-03-19 16:27:54] Write1 ==> Rendering finished
[2018-03-19 16:27:54] QApplication::qAppName: Please instantiate the QApplication object first
[2018-03-19 16:27:59] Crash reporter process does not seem to be responding anymore. This pipe IPC_COM might be used somewhere else.