title: Tried updating conda but got an error Cannot link a source that does not exist
body: <p>I've tried updating conda using the command <code>conda updade conda</code> but I get an error:</p>
  
  <pre><code>ERROR conda.core.link:_execute_actions(337): An error occurred while installing package 'defaults::tqdm-4.42.1-py_0'.
  CondaError: Cannot link a source that does not exist. C:\Users\User\Anaconda3\Scripts\conda.exe
  Running `conda clean --packages` may resolve your problem.
  Attempting to roll back.
  
  
  CondaError: Cannot link a source that does not exist. C:\Users\User\Anaconda3\Scripts\conda.exe
  Running `conda clean --packages` may resolve your problem.
  </code></pre>