"BadValueError: Property xxxx is not multi-line" on db.TextProperty()

I'm using python, django and google app engine and I'm getting the error below. However, bookdescription is a TextProperty not a StringProperty so I don't understand why the multi-line error is happening.

The error is intermittent, sometimes the page will render fine, sometimes not. I'm new to coding so any and all help is very much appreciated!

Model definition looks like this:

class Book(db.Model):
    list = db.ReferenceProperty(List)
    booktitle = db.StringProperty()
    bookauthor = db.StringProperty()
    bookdescription = db.TextProperty()
    added = db.DateTimeProperty(auto_now_add=True)

Full error:

Property bookdescription is not multi-line 
Traceback (most recent call last): 
  File "/base/python_runtime/python_lib/versions/1/google/appengine/ 
ext/webapp/__init__.py", line 511, in __call__ 
    handler.get(*groups) 
  File "/base/data/home/apps/7-books/3.345967110627358311/7books.py", 
line 279, in get 
    self.response.out.write(template.render(path, template_values)) 
  File "/base/python_runtime/python_lib/versions/1/google/appengine/ 
ext/webapp/template.py", line 81, in render 
    return t.render(Context(template_dict)) 
  File "/base/python_runtime/python_lib/versions/1/google/appengine/ 
ext/webapp/template.py", line 121, in wrap_render 
    return orig_render(context) 
  File "/base/python_runtime/python_lib/versions/third_party/ 
django-0.96/django/template/__init__.py", line 168, in render 
    return self.nodelist.render(context) 
  File "/base/python_runtime/python_lib/versions/third_party/ 
django-0.96/django/template/__init__.py", line 705, in render 
    bits.append(self.render_node(node, context)) 
  File "/base/python_runtime/python_lib/versions/third_party/ 
django-0.96/django/template/__init__.py", line 718, in render_node 
    return(node.render(context)) 
  File "/base/python_runtime/python_lib/versions/third_party/ 
django-0.96/django/template/loader_tags.py", line 82, in render 
    return compiled_parent.render(context) 
  File "/base/python_runtime/python_lib/versions/third_party/ 
django-0.96/django/template/__init__.py", line 168, in render 
    return self.nodelist.render(context) 
  File "/base/python_runtime/python_lib/versions/third_party/ 
django-0.96/django/template/__init__.py", line 705, in render 
    bits.append(self.render_node(node, context)) 
  File "/base/python_runtime/python_lib/versions/third_party/ 
django-0.96/django/template/__init__.py", line 718, in render_node 
    return(node.render(context)) 
  File "/base/python_runtime/python_lib/versions/third_party/ 
django-0.96/django/template/loader_tags.py", line 23, in render 
    result = self.nodelist.render(context) 
  File "/base/python_runtime/python_lib/versions/third_party/ 
django-0.开发者_运维百科96/django/template/__init__.py", line 705, in render 
    bits.append(self.render_node(node, context)) 
  File "/base/python_runtime/python_lib/versions/third_party/ 
django-0.96/django/template/__init__.py", line 718, in render_node 
    return(node.render(context)) 
  File "/base/python_runtime/python_lib/versions/third_party/ 
django-0.96/django/template/defaulttags.py", line 99, in render 
    values = list(values) 
  File "/base/python_runtime/python_lib/versions/1/google/appengine/ 
ext/db/__init__.py", line 2012, in next 
    return self.__model_class.from_entity(self.__iterator.next()) 
  File "/base/python_runtime/python_lib/versions/1/google/appengine/ 
ext/db/__init__.py", line 1239, in from_entity 
    instance = cls(None, _from_entity=True, **entity_values) 
  File "/base/python_runtime/python_lib/versions/1/google/appengine/ 
ext/db/__init__.py", line 813, in __init__ 
    prop.__set__(self, value) 
  File "/base/python_runtime/python_lib/versions/1/google/appengine/ 
ext/db/__init__.py", line 542, in __set__ 
    value = self.validate(value) 
  File "/base/python_runtime/python_lib/versions/1/google/appengine/ 
ext/db/__init__.py", line 2453, in validate 
    raise BadValueError('Property %s is not multi-line' % self.name) 
BadValueError: Property bookdescription is not multi-line

Class looks like this:

class Displaylist(webapp.RequestHandler):

    def get(self, id):

        booklist = List.get_by_id(int(id))

        books = booklist.book_set

        list = booklist
        creator = booklist.user
        location = getip(self.request.remote_addr)
        tld = gettld(location)
        aff = getaff(location)

        user = users.get_current_user()

        if user:
            loginout = users.create_logout_url("/")
            username = user.email()
        else:
            loginout = users.create_login_url("/")
            username = ''

        template_values = {
            'list': list,
            'creator': creator,
            'books': books,
            'email': username,
            'loginout': loginout,
            'tld': tld,
            'aff': aff,
            }

        path = os.path.join(os.path.dirname(__file__), 'templates/list.html')
        self.response.out.write(template.render(path, template_values))

---

It seems like the runtime environment is somehow referring to a different definition of the Book model which has bookdescription defined as a StringProperty because the error is being raised from the StringProperty.validate() function.

Do you have the Book model defined in multiple places by any chance?