错误：安装 devtools 时“‘devtools’的包或命名空间加载失败”答案

【问题标题】：Error: "package or namespace load failed for ‘devtools’" when installing devtools错误：安装 devtools 时“‘devtools’的包或命名空间加载失败”
【发布时间】：2020-06-03 17:16:58
【问题描述】：

Devtools 安装失败。当我运行函数时：

install.packages("devtools")

R 告诉我包已成功解包。但是当我运行 library(devtools) 时 - 我收到一条错误消息（见下文）。

完整的控制台：

`>install.packages("devtools")
Installing package into ‘C:/Users/fallo/OneDrive/Documents/R/win-library/3.6’
(as ‘lib’ is unspecified)
trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.6/devtools_2.2.2.zip'
Content type 'application/zip' length 351954 bytes (343 KB)
downloaded 343 KB

package ‘devtools’ successfully unpacked and MD5 sums checked

The downloaded binary packages are in
    C:\Users\fallo\AppData\Local\Temp\Rtmp2Ddudk\downloaded_packages
> library(devtools)
Error: package or namespace load failed for ‘devtools’:
 .onLoad failed in loadNamespace() for 'pkgload', details:
  call: loadNamespace(i, c(lib.loc, .libPaths()), versionCheck = vI[[i]])
  error: namespace ‘rlang’ 0.4.0 is already loaded, but >= 0.4.1 is required`> install.packages("devtools")
Installing package into ‘C:/Users/fallo/OneDrive/Documents/R/win-library/3.6’
(as ‘lib’ is unspecified)
trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.6/devtools_2.2.2.zip'
Content type 'application/zip' length 351954 bytes (343 KB)
downloaded 343 KB

package ‘devtools’ successfully unpacked and MD5 sums checked

The downloaded binary packages are in
    C:\Users\fallo\AppData\Local\Temp\Rtmp2Ddudk\downloaded_packages
> library(devtools)
Error: package or namespace load failed for ‘devtools’:
 .onLoad failed in loadNamespace() for 'pkgload', details:
  call: loadNamespace(i, c(lib.loc, .libPaths()), versionCheck = vI[[i]])
  error: namespace ‘rlang’ 0.4.0 is already loaded, but >= 0.4.1 is required

【问题讨论】：

转到 RStudio 顶部的 session，然后转到 Restart R 或 Ctrl+Shift+F10 或关闭并重新打开 RStudio

标签： r installation devtools

【解决方案1】：

我不知道是什么导致了这个特殊问题，但就我而言，它是在我安装 Rtools 来安装一些软件包时发生的。最终，它开始对许多软件包给出相同的错误。完全删除 R 并重新安装它解决了我的问题。

【讨论】：