I am sorry for not responding so long.
Regarding code. Well, before sharing, let me highlight something.
The app runs perfectly on my laptop, (Windows 8.1), using desktop r-studio. It also opens via the r-studio server, established on Azure Droplet, (Ubuntu). Described error occurs only when I am trying to run an app using shiny-server, established on the same VM.
I am pretty sure that recursion is not an issue. I checked shiny-server logs. The application fails when trying to load a large r-data object into the global environment.
So, taking into account everything that I mentioned, the line of code that causing the issue is following:
load('SavedDataImage.RData')