title: Batch file `start` command fails if `cmd` not called
body: <p>A <code>.bat</code> script that launches a program stopped working today on Windows 10 Pro 21H1.</p>
  <p>Investigating, <a href="https://github.com/winnfsd/vagrant-winnfsd/blob/master/bin/nfsservice.bat" rel="nofollow noreferrer">the batch file</a> contains <code>start &quot;&quot; &quot;%~dp0winnfsd&quot; -log %2 -pathFile %3 -id %4 %5</code> which filled in is:</p>
  <pre><code>start &quot;&quot; &quot;C:\Users\Peter\.vagrant.d\gems\2.6.7\gems\vagrant-winnfsd-1.4.0\bin\winnfsd&quot; -log on -pathFile &quot;C:/Users/Peter/.vagrant.d/nfspaths&quot; -id 0 0
  </code></pre>
  <p>When this is executed from a batch file or command prompt, today it gives the error:</p>
  <pre><code>The filename, directory name, or volume label syntax is incorrect.
  
  Press Enter or Esc to exit...
  </code></pre>
  <p>If I remove <code>start &quot;&quot;</code> and run the command from the command prompt it works:</p>
  <pre><code>&quot;C:\Users\Peter\.vagrant.d\gems\2.6.7\gems\vagrant-winnfsd-1.4.0\bin\winnfsd&quot; -log on -pathFile &quot;C:/Users/Peter/.vagrant.d/nfspaths&quot; -id 0 0
  </code></pre>
  <p>And after reading <a href="https://stackoverflow.com/a/8351295/119750">https://stackoverflow.com/a/8351295/119750</a> I modified the batch file to contain this and it works:</p>
  <pre><code>start cmd /c call &quot;C:\Users\Peter\.vagrant.d\gems\2.6.7\gems\vagrant-winnfsd-1.4.0\bin\winnfsd.exe&quot; -log on -pathFile &quot;C:/Users/Peter/.vagrant.d/nfspaths&quot; -id 0 0
  </code></pre>
  <p>I don't understand what's going on here or why the first has stopped working.</p>
  <ol>
  <li>Why would the first command not work/stop working?</li>
  <li>Why does calling <code>cmd</code> make a difference?</li>
  </ol>