title: Part of numpy and scipy will not install on Windows due to missing source
body: <p>conda install numpy</p>
  
  <p>ERROR conda.core.link:_execute_actions(337): An error occurred while installing package 'defaults::tqdm-4.38.0-py_0'. CondaError: Cannot link a source that does not exist.</p>
  
  <p>conda install scipy</p>
  
  <p>ERROR conda.core.link:_execute_actions(337): An error occurred while installing package 'defaults::tqdm-4.38.0-py_0'. CondaError: Cannot link a source that does not exist.</p>
  
  <p>conda clean –packages   did not help</p>