Django raises some of its own exceptions as well as standard Python exceptions.
Django Core Exceptions
Django core exception classes are defined in
- exception AppRegistryNotReady
- This exception is raised when attempting to use models before the app loading process, which initializes the ORM, is complete.
- exception EmptyResultSet
EmptyResultSet may be raised during query generation if a query won’t return any results. Most Django projects won’t encounter this exception, but it might be useful for implementing custom lookups and expressions.
- exception FieldDoesNotExist
FieldDoesNotExist exception is raised by a model’s
_meta.get_field() method when the requested field does not exist on the model or on the model’s parents.
- exception MultipleObjectsReturned
The MultipleObjectsReturned exception is raised by a query if only one object is expected, but multiple objects are returned. A base version of this exception is provided in django.core.exceptions; each model class contains a subclassed version that can be used to identify the specific object type that has returned multiple objects.
See get() for further information.
- exception SuspiciousOperation
The SuspiciousOperation exception is raised when a user has performed an operation that should be considered suspicious from a security perspective, such as tampering with a session cookie. Subclasses of
SuspiciousOperation exception reaches the WSGI handler level it is logged at the
Error level and results in a HttpResponseBadRequest. See the logging documentation for more information.
- exception PermissionDenied
- The PermissionDenied exception is raised when a user does not have permission to perform the action requested.
- exception ViewDoesNotExist
- The ViewDoesNotExist exception is raised by django.urls when a requested view does not exist.
- exception MiddlewareNotUsed
- The MiddlewareNotUsed exception is raised when a middleware is not used in the server configuration.
- exception ImproperlyConfigured
- The ImproperlyConfigured exception is raised when Django is somehow improperly configured – for example, if a value in
settings.py is incorrect or unparseable.
- exception FieldError
- The FieldError exception is raised when there is a problem with a model field. This can happen for several reasons:
- A field in a model clashes with a field of the same name from an abstract base class
- An infinite loop is caused by ordering
- A keyword cannot be parsed from the filter parameters
- A field cannot be determined from a keyword in the query parameters
- A join is not permitted on the specified field
- A field name is invalid
- A query contains invalid order_by arguments
- exception ValidationError
- The ValidationError exception is raised when data fails form or model field validation. For more information about validation, see Form and Field Validation, Model Field Validation and the Validator Reference.
ValidationErrors that don’t belong to a particular field in a form or model are classified as
NON_FIELD_ERRORS. This constant is used as a key in dictionaries that otherwise map fields to their respective list of errors.
URL Resolver exceptions
URL Resolver exceptions are defined in
- exception NoReverseMatch
- The NoReverseMatch exception is raised by django.urls when a matching URL in your URLconf cannot be identified based on the parameters supplied.
Database exceptions may be imported from
Django wraps the standard database exceptions so that your Django code has a guaranteed common implementation of these classes.
- exception Error
- exception InterfaceError
- exception DatabaseError
- exception DataError
- exception OperationalError
- exception IntegrityError
- exception InternalError
- exception ProgrammingError
- exception NotSupportedError
The Django wrappers for database exceptions behave exactly the same as the underlying database exceptions. See PEP 249, the Python Database API Specification v2.0, for further information.
As per PEP 3134, a
__cause__ attribute is set with the original (underlying) database exception, allowing access to any additional information provided.
- exception models.ProtectedError
Raised to prevent deletion of referenced objects when using django.db.models.PROTECT. models.ProtectedError is a subclass of IntegrityError.
Http exceptions may be imported from
- exception UnreadablePostError
- UnreadablePostError is raised when a user cancels an upload.
Transaction exceptions are defined in
- exception TransactionManagementError
- TransactionManagementError is raised for any and all problems related to database transactions.
Testing Framework Exceptions
Exceptions provided by the
- exception client.RedirectCycleError
- RedirectCycleError is raised when the test client detects a loop or an overly long chain of redirects.
Django raises built-in Python exceptions when appropriate as well. See the Python documentation for further information on the bltin-exceptions.