Problem installing ROS2

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I am trying to install ROS2 on Ubuntu 18.04 via apt get, following the installation guide on ROS2 website. However, I keep getting error

failed to load shared library of rmw implementation

I am following the tutorial and sourcing all the required config files. I have searched google for the same error text, but the best advice there is to source some files and I am already doing that. Would be grateful for any help, thank you.