actually I have a problem in installing packages. i dont know how does this error comes. i am using R 3.4.2 version and when I install the packages "Error in readRDS(file) : unknown input format". Error in file(filename, "r", encoding = encoding) : 
  cannot open the connection
In addition: Warning message:
In file(filename, "r", encoding = encoding) : InternetOpenUrl failed: ''this wasthe other error tat i am getting and i couldnt install LIMMA package. can anyone help me in rectifying my mistakes.

> source("https://bioconductor.org/biocLite.R")
Error in file(filename, "r", encoding = encoding) : 
  cannot open the connection
In addition: Warning message:
In file(filename, "r", encoding = encoding) : InternetOpenUrl failed: ''
> help()
starting httpd help server ... done
> utils:::menuInstallPkgs()
--- Please select a CRAN mirror for use in this session ---
Error in readRDS(file) : unknown input format
Error in readRDS(file) : unknown input format
Error in readRDS(file) : unknown input format
Error in readRDS(file) : unknown input format
Error in readRDS(file) : unknown input format 

package ‘aroma.affymetrix’ successfully unpacked and MD5 sums checked

The downloaded binary packages are in
        C:\Users\sreenivas reddy\AppData\Local\Temp\RtmpsnjUM5\downloaded_packages
> utils:::menuInstallPkgs()
Error in readRDS(file) : unknown input format
Error in readRDS(file) : unknown input format
Error in readRDS(file) : unknown input format
Error in readRDS(file) : unknown input format

Error in readRDS(file) : unknown input format
Error in readRDS(file) : unknown input format
Warning: dependency ‘impute’ is not available
trying URL 'http://ftp.iitm.ac.in/cran/bin/windows/contrib/3.4/samr_2.0.zip'
Content type 'application/zip' length 122732 bytes (119 KB)
downloaded 119 KB

package ‘samr’ successfully unpacked and MD5 sums checked