In our application the method WindowScopeManager$ScopeMap.disactivateIfUnused always throws a NullPointerException. The exception is caught in the calling method determineWindowID, which is why this is not so obvious.

This happens once a window is opened and once it is closed.

Code:
        private void disactivateIfUnused(FacesContext facesContext) {
            if (!EnvUtils.containsBeans(this) && !EnvUtils.containsDisposedBeans(facesContext.getViewRoot().getViewMap())) {
                //the map *does not* contain objects (most probably beans) other than the ones inserted by the framework
                disactivate(getState(facesContext));
            }
        }

Root cause:
In our application facesContext.getViewRoot() is always null.

Resolution:
Implement a null check for facesContext.getViewRoot() in disactivateIfUnused.

Impacts:
- Our DynaTrace outputs are polluted with that NullPointerException. It may lead to wrong assumptions when debugging non-related defects that always occur afterwards.
- Disactivate will never be called, even there are no beans in the map and no beans have a @WindowDisposed annotation.

For us the latter is not relevant, because we use @WindowDisposed. But: Please evaluate what impact this might have on others.

Furthermore:
- Check whether you may get the viewMap a different way. (To me that code looks strange.)
- The calling WindowScopeManager.disposeWindow catches this NullPointerException with "catch (Throwable e)". IMHO this must be "catch (RuntimeException e)". Please fix immediately with this bug. Similar code smell a few lines below.