title: How to fix django admin "add" button
body: <p>I'm new to web development, and i'm building a blog web app in Django.
  I'm having problems adding new posts through django-admin. Clicking the "add" button gives me an <code>"Error during template rendering - 'str' object has no attribute 'utcoffset'"</code> error message.</p>
  
  <p>models.py</p>
  
  <pre><code>
  from django.db import models
  from django.utils import timezone
  import datetime
  
  # Create your models here.
  
  
  class Post(models.Model):
      title = models.CharField(max_length=50)
      content = models.TextField(blank=True, null=True)
      post_date = models.DateTimeField(default='date posted')
  
      def published_recently(self):
          now = timezone.now()
          return now - datetime.timedelta(days=1) &lt;= self.post_date &lt;= now
      published_recently.admin_order_field = 'post_date'
      published_recently.boolean = True
      published_recently.short_description = 'Recent post?'
  
      def __str__(self):
          return self.title
  
  
  class Customer(models.Model):
      username = models.CharField(max_length=50)
      firstname = models.CharField(max_length=50)
      lastname = models.CharField(max_length=50)
      email = models.CharField(max_length=50)
      country = models.CharField(max_length=50)
      reg_date = models.DateTimeField(default='date reg')
  
      def __str__(self):
          return self.username
  
  
  class Comment(models.Model):
      comment_cont = models.TextField(max_length=200)
      user_name = models.ForeignKey(Customer, default=0, on_delete=models.CASCADE)
      comment_post = models.ForeignKey(Post, on_delete=models.CASCADE)
      votes = models.BigIntegerField(default=0)
      comment_date = models.DateTimeField(default='date commented')
  
      def __str__(self):
          return self.comment_cont
  
  
  class Feedback(models.Model):
      feedback_title = models.CharField(max_length=50)
      feedback_detail = models.CharField(max_length=200)
      user_name = models.ForeignKey(Customer, default=1, verbose_name='user_name', on_delete=models.SET_DEFAULT)
  </code></pre>
  
  <p>admin.py</p>
  
  <pre><code>
  from django.contrib import admin
  from .models import Post, Customer, Feedback, Comment
  
  
  # Register your models here.
  class CommentInLine(admin.TabularInline):
      model = Comment
      extra = 1
      fields = ['comment_cont', 'votes', 'comment_date']
  
  
  class CustomerAdmin(admin.ModelAdmin):
      fieldsets = [
          (None, {'fields': ['firstname', 'lastname', 'username', 'email', 'country', 'reg_date']})
      ]
  
  
  class PostAdmin(admin.ModelAdmin):
      fieldsets = [
          ('Post', {'fields': ['title', 'content']}),
          ('Date information', {'fields': ['post_date'], 'classes':['collapse']}),
      ]
      inlines = [CommentInLine]
      list_display = ('title', 'content', 'post_date', 'published_recently')
      list_filter = ['post_date']
      search_fields = ['title']
  
  
  class FeedbackAdmin(admin.ModelAdmin):
      fieldsets = [
          ('Feedback', {'fields': ['feedback_title', 'feedback_detail', 'user_name']}),
      ]
      list_display = ('user_name', 'feedback_title', 'feedback_detail')
  #     inlines = [CustomerInLine]
  #     list_display = ('user_name', 'feedback_title', 'feedback_detail')
  
  
  class CommentAdmin(admin.ModelAdmin):
      fields = ['user_name', 'comment_post', 'comment_cont', 'votes', 'comment_date']
  
  
  admin.site.register(Post, PostAdmin)
  admin.site.register(Feedback, FeedbackAdmin)
  admin.site.register(Customer, CustomerAdmin)
  admin.site.register(Comment, CommentAdmin)
  </code></pre>
  
  <p>I want to be able to add posts through Django admin. Any other corrections to the code is highly welcome. I appreciate the help. Thanks.</p>