R Package installed but cannot be loaded?

问题

I installed the "digest" package in R.

> install.packages("digest")
Installing package into ‘C:/Users/user/Documents/R/win-library/3.3’
(as ‘lib’ is unspecified)
trying URL 'https://mran.microsoft.com/snapshot/2017-03-15/bin/windows/contrib/3.3/digest_0.6.12.zip'
Content type 'application/zip' length 172746 bytes (168 KB)
downloaded 168 KB

package ‘digest’ successfully unpacked and MD5 sums checked
Warning in install.packages :
  cannot remove prior installation of package ‘digest’

The downloaded binary packages are in
    C:\Users\user\AppData\Local\Temp\RtmpaMPhK6\downloaded_packages

I confirmed that this package is installed in:

C:\Program Files\R\R-3.3.2\library\digest

My repos are:

getOption("repos")

                                            CRAN                                        CRANextra 
"https://mran.microsoft.com/snapshot/2017-03-15"             "http://www.stats.ox.ac.uk/pub/RWin" 

Then I wanted to install "kableExtra" package. But I am getting an error message that the there is no "digest":

 > library(kableExtra)
    Error in loadNamespace(i, c(lib.loc, .libPaths()), versionCheck = vI[[i]]) : 
      there is no package called ‘digest’
    Error: package or namespace load failed for ‘kableExtra’

What is wrong? Is this due to the fact that the original library is from CRAn, but for some reason this "digest" package is coming from MRAN? How can I fix this?

来源：https://stackoverflow.com/questions/46494336/r-package-installed-but-cannot-be-loaded