几天前，我已经将R（从3.6升级到4.0）和RStudio（从1.1升级到1.2.5），昨天将Ubuntu从18.04升级到20.04。
Since then, R sometimes never terminates when executing certain commands: ivreg (from package AER), summary (of a logit regression) and logitmfx (from package mfx). Sometimes these commands run fine, but most of the time I have to kill the process (killall rstudio) because R won't terminate the execution, even when pressing the red Stop button in RStudio.
When I tried example('AER'), it worked fine. Then I re-installed the package AER. It threw 10 warnings of type In readLines(file, skipNul = TRUE) : cannot open compressed file '/usr/lib/R/site-library/[package]/DESCRIPTION', probable reason 'No such file or directory' where [package] is abind, colorspace, dichromat... (but not AER).
Since then example('AER') throws a warning: no help found for ‘AER’.
I've removed and reinstalled R 4.0: it didn't help. Besides, the apt purge r-base* r-recommended r-cran-* threw a warning: dpkg: warning: while removing r-base-core, directory '/usr/lib/R/site-library' not empty so not removed. Also, there was a bunch of Package [package] is not installed, so not removed, including for [package] equal to r-cran-abind and the other listed above (this purge also returned a bunch of Note, selecting [package] for glob 'r-cran-*').
我没有在没有RStudio的情况下尝试使用R。在升级到Ubuntu 20.04时，我可能正在RStudio上工作。另外，我不记得是在升级R和RStudio之后（这是我的最佳猜测）还是在升级Ubuntu（一两天之后）之后开始出现此问题。
我希望有人能帮帮忙。
