I mean the up to three KNIME extensions about R as mentioned before. I would deinstall them an install them again. Maybe first only using the “R Scripting extension”
From my experience the most important thing is to update RServe to the latest version (1.8-6). You will have to compile the package yourself (depending on your platform) since there is no binary version ready for download (yet).
http://www.rforge.net/Rserve/files/
Download the .tar file and use it to install a package from Archive and install it via RStudio:
You will need additional tools in order to compile the packages. For MacOS these are:
https://cran.r-project.org/bin/macosx/tools/
For Windows you have Rtools
https://cloud.r-project.org/bin/windows/Rtools/
For RServe on Windows there are special hints. With the latest version I have not encountered any problems between R and KNIME on Windows but if you still have problems it might be worth checking this out:
http://www.rforge.net/Rserve/rserve-win.html
And as mentioned in another post when compiling on Windows make sure you do not use too complicated paths for your version of RTools:
Yes I know it is a bit of a puzzle but you will have the full power of R at your disposal within KNIME in the end.