title: Error: package or namespace load failed, object ... not found
body: <p>I am running a new install of R (3.5.0) and RStudio (1.1.414). [Note I have now updated to 3.5.1 and 1.1.453 and am still experiencing the issues below with the exception of the "built under R version 3.5.1" warning messages]</p>
  
  <p>I have installed the rlang package using <code>install.packages("rlang")</code> without encountering any issues but when I attempt to load the package I get the following error</p>
  
  <p><code>Error: package or namespace load failed for ‘rlang’:
   .onLoad failed in loadNamespace() for 'rlang', details:
    call: dots_list(...)
    error: object 'rlang_dots_list' not found
  In addition: Warning message:
  package ‘rlang’ was built under R version 3.5.1</code></p>
  
  <p>I've uninstalled and reinstalled rlang (closing restarting RStudio in between each command) and am still encountering this error.</p>
  
  <p>I am also encountering a set of similar (although possible totally unrelated) issue with other packages</p>
  
  <ol>
  <li><p>RStudio provides the following warning every startup</p>
  
  <pre><code>[Workspace loaded from ~/.RData]
  
  Error in yaml.load(readLines(con), error.label = error.label, ...) : 
     object 'C_unserialize_from_yaml' not found
  Error in yaml.load(readLines(con), error.label = error.label, ...) : 
    object 'C_unserialize_from_yaml' not found
  </code></pre></li>
  <li><p>library(devtools) gives the following errors</p>
  
  <pre><code>Error: package or namespace load failed for ‘devtools’ in FUN(X[[i]], ...):
   no such symbol digest in package //[redacted]/My 
  Documents/R/win-library/3.5/digest/libs/x64/digest.dll
  In addition: Warning message:
  package ‘devtools’ was built under R version 3.5.1 
  </code></pre></li>
  </ol>
  
  <hr>
  
  <p>Someone on twitter asked for the results of <code>packageDescription("rlang")</code></p>
  
  <p>I've copied the output below in case it helps with troubleshooting.</p>
  
  <pre><code>Package: rlang
  Version: 0.2.1
  Title: Functions for Base Types and Core R and 'Tidyverse' Features
  Description: A toolbox for working with base types, core R features like the condition system, and core
          'Tidyverse' features like tidy evaluation.
  Authors@R: c( person("Lionel", "Henry", ,"lionel@rstudio.com", c("aut", "cre")), person("Hadley", "Wickham",
          ,"hadley@rstudio.com", "aut"), person("RStudio", role = "cph") )
  License: GPL-3
  LazyData: true
  ByteCompile: true
  Depends: R (&gt;= 3.1.0)
  Suggests: crayon, knitr, methods, pillar, rmarkdown (&gt;= 0.2.65), testthat, covr
  RoxygenNote: 6.0.1
  URL: http://rlang.tidyverse.org, https://github.com/r-lib/rlang
  BugReports: https://github.com/r-lib/rlang/issues
  NeedsCompilation: yes
  Packaged: 2018-05-30 13:14:55 UTC; lionel
  Author: Lionel Henry [aut, cre], Hadley Wickham [aut], RStudio [cph]
  Maintainer: Lionel Henry &lt;lionel@rstudio.com&gt;
  Repository: CRAN
  Date/Publication: 2018-05-30 14:23:07 UTC
  Built: R 3.5.1; x86_64-w64-mingw32; 2018-07-02 15:08:55 UTC; windows
  
  -- File: [redacted]/My Documents/R/win-library/3.5/rlang/Meta/package.rds 
  </code></pre>