title: Error attaching rstan package: Entry Point Not Found
body: <p>I've successfully installed rstan, but when I try to attach it with <code>library(rstan)</code> I get a pop-up window with the title &quot;RGui (64-bit): Rgui.exe - Entry Point Not Found&quot; and the message content</p>
  <blockquote>
  <p>The procedure entry point EXTPTR_PTR could not be located in the dynamic link library C:\Users\MyName\Documents\R\win-library\4.0\Rcpp\libs\x64\Rcpp.dll.</p>
  </blockquote>
  <p>In the R console itself I get</p>
  <pre><code>&gt; library(rstan)
  Loading required package: StanHeaders
  Loading required package: ggplot2
  Error: package or namespace load failed for ‘rstan’ in inDL(x, as.logical(local), as.logical(now), ...):
   unable to load shared object 'C:/Users/Daniel/Documents/R/win-library/4.0/Rcpp/libs/x64/Rcpp.dll':
    LoadLibrary failure:  The specified procedure could not be found.
  </code></pre>
  <p>I'm running 4.0.0 (2020-04-24) 'Arbor Day', on a 64 bit Windows machine with Windows 10.</p>
  <p>I thought this might have been an issue with Rtools (<a href="https://stackoverflow.com/questions/63020444/rtools-4-0-not-found-during-package-installation">Rtools 4.0 not found during package installation</a>), but having reinstalled rtools40 and properly added it to my path - and then reinstalling <em>all</em> of my packages to make sure there were no dependency issues - the problem with rstan persists. Any idea what might be going wrong here, and how I can get rstan working?</p>