Kernel Error in R Notebook using Jupyter Notebook

I was having exactly the same error in Windows 7. I added R to PATH environment variables and I was able to run it on shell but I was still having the kernel error in Jupyter.

The Kernel started working when installed system wide using:

IRkernel::installspec(user = FALSE)

instead of the first installation option:

IRkernel::installspec()

Note that it is necessary to set both parameters, the PATH variable and the R system wide install.