title: Flask-Migrate: alembic.util.CommandError: No such revision
body: <p>I have installed the Flask-Migration and initialised the migration however I would receive the following error when i run <code>python3 manage.py db migrate</code>.</p>
  
  <pre><code>File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/alembic/script.py", line 104, in get_revision
  raise util.CommandError("No such revision '%s'" % id_)
  alembic.util.CommandError: No such revision '38340accc10'
  </code></pre>
  
  <p>As suggested in <a href="https://stackoverflow.com/questions/20973145/cannot-complete-flask-migration">Cannot complete Flask-Migration</a> a possible reason would be that I have done an upgrade which generated the above revision '38340accc10', but then deleted whole migrations/ directory and removed all upgrade scripts. </p>
  
  <p>How do I delete the Alembic versions in my database? I have tried recreating the database with <code>db.drop_all()</code> and <code>db.create_all()</code> but the same error appears.</p>