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Issue solved. Thank you for the SQLite tip, it set me on the right path. It turns out though, that I needed to install mono-complete package and run Manager through mono. I did the following things:
1.I followed the instructions in this thread for “Installing Prerequisite Software” : https://forum.manager.io/t/manager-wont-start-ubuntu-14-04/75281
2.I installed mono-complete package
3.I ran the application using mono with command: sudo mono /opt/manager-accounting/ManagerDesktop.exe
I am now able to run the appcication, and I am indeed able to import the business as well which solves the original problem as well. Thanks for the help.