Fixed #20786 -- Cleaned up docs/ref/exceptions.txt

Django raises some Django specific exceptions as well as many standard

Python exceptions.

Django-specific Exceptions

==========================

Django Core Exceptions

======================

.. module:: django.core.exceptions

    :synopsis: Django specific exceptions

    :synopsis: Django core exceptions

Django core exception classes are defined in :mod:`django.core.exceptions`.

ObjectDoesNotExist and DoesNotExist

-----------------------------------

.. exception:: DoesNotExist

.. exception:: ObjectDoesNotExist

    The :exc:`DoesNotExist` exception is raised when an object is not found

    for the given parameters of a query.

    The ``DoesNotExist`` exception is raised when an object is not found for

    the given parameters of a query. Django provides a ``DoesNotExist``

    exception as an attribute of each model class to identify the class of

    object that could not be found and to allow you to catch a particular model

    class with ``try/except``.

.. exception:: ObjectDoesNotExist

    :exc:`ObjectDoesNotExist` is defined in :mod:`django.core.exceptions`.

    :exc:`DoesNotExist` is a subclass of the base :exc:`ObjectDoesNotExist`

    exception that is provided on every model class as a way of

    identifying the specific type of object that could not be found.

    The base class for ``DoesNotExist`` exceptions; a ``try/except`` for

    ``ObjectDoesNotExist`` will catch ``DoesNotExist`` exceptions for all

    models.

    See :meth:`~django.db.models.query.QuerySet.get()` for further information

    on :exc:`ObjectDoesNotExist` and :exc:`DoesNotExist`.

.. currentmodule:: django.core.urlresolvers

URL Resolver exceptions

=======================

URL Resolver exceptions are defined in :mod:`django.core.urlresolvers`.

NoReverseMatch

--------------

.. exception:: NoReverseMatch

Database Exceptions

===================

Database exceptions are provided in :mod:`django.db`.

Django wraps the standard database exceptions so that your Django code has a

guaranteed common implementation of these classes. These database exceptions

are provided in :mod:`django.db`.

guaranteed common implementation of these classes.

.. exception:: Error

.. exception:: InterfaceError

.. versionchanged:: 1.6

    Previous version of Django only wrapped ``DatabaseError`` and

    Previous versions of Django only wrapped ``DatabaseError`` and

    ``IntegrityError``, and did not provide ``__cause__``.

.. exception:: models.ProtectedError

Raised to prevent deletion of referenced objects when using

:attr:`django.db.models.PROTECT`. Subclass of :exc:`IntegrityError`.

:attr:`django.db.models.PROTECT`. :exc:`models.ProtectedError` is a subclass

of :exc:`IntegrityError`.

.. currentmodule:: django.http

Http Exceptions

===============

Http exceptions are provided in :mod:`django.http`.

.. exception:: UnreadablePostError

    The :exc:`UnreadablePostError` is raised when a user cancels an upload.

    It is available from :mod:`django.http`.

.. currentmodule:: django.db.transaction

Transaction Exceptions

======================

Transaction exceptions are defined in :mod:`django.db.transaction`.

.. exception:: TransactionManagementError

    The :exc:`TransactionManagementError` is raised for any and all problems

    related to database transactions. It is available from

    :mod:`django.db.transaction`.

    related to database transactions.

Python Exceptions

=================