R iconv() error -unsupported conversion from 'latin1' to 'ASCII'

Question

I want to install the R package "doMC", and the code is

install.packages("doMC", repos="http://R-Forge.R-project.org")

and then I get the following error:

Error in iconv(x, "latin1", "ASCII") : unsupported conversion from 'latin1' to 'ASCII'

So, how do I resolve the issue?

My OS is :

Linux version 2.6.32-504.el6.x86_64 ([email protected]) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-11) (GCC) ) #1 SMP Tue Sep 16 01:56:35 EDT 2014

and my R version :

R version 3.2.3 (2015-12-10) -- "Wooden Christmas-Tree"