title: ssh-add : Invalid key length
body: <p>After my mac upgraded automatically, I try ssh-add fail:</p>
  
  <pre><code>&gt;ssh-add
  Enter passphrase for /Users/dan/.ssh/id_rsa:
  Error loading key "/Users/dan/.ssh/id_rsa": Invalid key length
  
  &gt;ssh -V
  OpenSSH_7.6p1, LibreSSL 2.6.2
  </code></pre>
  
  <p>But how can I fix this issue?</p>
  
  <p>Thanks!</p>