title: m2crypto generated certificate file "This file is invalid for use as the following: security certificate" error
body: <p>My python application is using M2Crypto to generate CSR in client, sends it to server and retrieves signed certificate in PEM format and saves as file.</p>
  
  <p>Signed certificate file can be verified by M2Crypto. It can be read by OpenSSL successfully both in client and server. </p>
  
  <p>However Windows clients report "<code>This file is invalid for use as the following: security certificate</code>" error when it is tried to be used. Like wise, in Ubuntu clients, "<code>Could not display &lt;filename&gt;</code>" is reported when it is tried to be viewed. </p>
  
  <p>Platform Information for both client and server:</p>
  
  <ul>
  <li>Python 2.7.x </li>
  <li>M2Crypto 0.21.1</li>
  <li>OpenSSL 1.0.1e</li>
  </ul>
  
  <p>Do you have any idea, what am I missing?</p>