title: Django: Server Error (500) when trying to add an instance of a model
body: <p>When I go on <code>localhost:8000/admin</code> and click on "Quotes   +ADD" it shows me error 500 instead of the editing interface. "Posts" works well. I just want to know if, without seeing the code, you could just tell me the different possible sources of this problem ?
  <a href="https://i.stack.imgur.com/xjJWn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xjJWn.png" alt="enter image description here"></a></p>
  
  <p>EDIT: Here are <code>models.py</code> and <code>admin.py</code>:</p>
  
  <p><strong>models.py</strong></p>
  
  <pre><code>class TimestampedModel(models.Model):
  
      created = models.DateTimeField(auto_now_add = True)
      updated = models.DateTimeField(auto_now = True)
  
      class Meta:
          abstract = True
  
  
  # Create your models here.
  class Post(TimestampedModel):
  
      title = models.CharField(max_length = 255, default='')
  
      intro = models.TextField(default='')
      title_one = models.TextField(default='')
      text_one = models.TextField(default='')
      title_two = models.TextField(default='')
      text_two = models.TextField(default='')
      title_three = models.TextField(default='')
      text_three = models.TextField(default='')
  
      def __repr__(self):
          return self.title
  
  class Quote(models.Model):
      quote = models.TextField(default='')
      author = models.CharField(max_length = 60, default='')
  
      def __repr__(self):
          return self.quote
  </code></pre>
  
  <p><strong>admin.py</strong></p>
  
  <pre><code>from django.contrib import admin
  from .models import Post, Quote
  
  # Register your models here.
  admin.site.register(Post)
  admin.site.register(Quote)
  </code></pre>
  
  <p>I also would like to let you know that when I try to make migrations and then migrate, it says "No changes detected".</p>
  
  <pre><code>ProgrammingError at /admin/blog/quote/
  
  relation "blog_quote" does not exist
  LINE 1: SELECT COUNT(*) AS "__count" FROM "blog_quote"
  </code></pre>