title: Something went wrong while saving this configuration: Unable to load theme by specified key: 'pure'
body: <p>i just to install the magento 2.1.i migrate my database thank to the tool provide by magento.it works great!!</p>
  
  <p>but the problem, when i running the frontend i get this error:
  <code>Unable to load theme by specified key: 'pure'</code></p>
  
  <p>and when i want to change the theme in administration, i get this error : <code>Something went wrong while saving this configuration: Unable to load theme by specified key: 'pure'</code></p>
  
  <p>i follow many tips such as to empty the table 'change_design', use this command :</p>
  
  <p>di:compile
  setup:upgrade
  setup:static-content:deploy
  indexer:reindex
  cache:flush
  ...</p>
  
  <p>but the problem persist.</p>
  
  <p>do you a know a solution to resolve this problem?
  thanks.</p>
  
  <p>ps: 'Pure' is the theme I was using on the website 1.9</p>