Django Exceptions

Django raises some of its own exceptions as well as standard Python exceptions.

Django Core Exceptions

Django core exception classes are defined in django.core.exceptions.

AppRegistryNotReady

• exception AppRegistryNotReady[source]
• This exception is raised when attempting to use models before the apploading process, which initializes the ORM, iscomplete.

ObjectDoesNotExist

• exception ObjectDoesNotExist[source]
• The base class for DoesNotExist exceptions;a try/except for ObjectDoesNotExist will catchDoesNotExist exceptions for all models.

See get() for further informationon ObjectDoesNotExist and DoesNotExist.

EmptyResultSet

• exception EmptyResultSet[source]
• EmptyResultSet may be raised during query generation if a query won’treturn any results. Most Django projects won’t encounter this exception,but it might be useful for implementing custom lookups and expressions.

FieldDoesNotExist

• exception FieldDoesNotExist[source]
• The FieldDoesNotExist exception is raised by a model’s_meta.get_field() method when the requested field does not exist on themodel or on the model’s parents.

MultipleObjectsReturned

• exception MultipleObjectsReturned[source]
• The MultipleObjectsReturned exception is raised by a query if onlyone object is expected, but multiple objects are returned. A base versionof this exception is provided in django.core.exceptions; each modelclass contains a subclassed version that can be used to identify thespecific object type that has returned multiple objects.

See get() for further information.

SuspiciousOperation

• exception SuspiciousOperation[source]

• The SuspiciousOperation exception is raised when a user hasperformed an operation that should be considered suspicious from a securityperspective, such as tampering with a session cookie. Subclasses ofSuspiciousOperation include:

  • DisallowedHost
  • DisallowedModelAdminLookup
  • DisallowedModelAdminToField
  • DisallowedRedirect
  • InvalidSessionKey
  • RequestDataTooBig
  • SuspiciousFileOperation
  • SuspiciousMultipartForm
  • SuspiciousSession
  • TooManyFieldsSentIf a SuspiciousOperation exception reaches the WSGI handler level it islogged at the Error level and results ina HttpResponseBadRequest. See the loggingdocumentation for more information.

PermissionDenied

• exception PermissionDenied[source]
• The PermissionDenied exception is raised when a user does not havepermission to perform the action requested.

ViewDoesNotExist

• exception ViewDoesNotExist[source]
• The ViewDoesNotExist exception is raised bydjango.urls when a requested view does not exist.

MiddlewareNotUsed

• exception MiddlewareNotUsed[source]
• The MiddlewareNotUsed exception is raised when a middleware is notused in the server configuration.

ImproperlyConfigured

• exception ImproperlyConfigured[source]
• The ImproperlyConfigured exception is raised when Django issomehow improperly configured – for example, if a value in settings.pyis incorrect or unparseable.

FieldError

• exception FieldError[source]

• The FieldError exception is raised when there is a problem with amodel field. This can happen for several reasons:

  • A field in a model clashes with a field of the same name from anabstract 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 queryparameters
  • A join is not permitted on the specified field
  • A field name is invalid
  • A query contains invalid order_by arguments

ValidationError

• exception ValidationError[source]
• The ValidationError exception is raised when data fails form ormodel field validation. For more information about validation, seeForm and Field Validation,Model Field Validation and theValidator Reference.

NON_FIELD_ERRORS

• NON_FIELD_ERRORS
• ValidationErrors that don’t belong to a particular field in a formor model are classified as NON_FIELD_ERRORS. This constant is usedas a key in dictionaries that otherwise map fields to their respectivelist of errors.

RequestAborted

• exception RequestAborted[source]
• New in Django 3.0:

The RequestAborted exception is raised when a HTTP body being readin by the handler is cut off midstream and the client connection closes,or when the client does not send data and hits a timeout where the servercloses the connection.

It is internal to the HTTP handler modules and you are unlikely to seeit elsewhere. If you are modifying HTTP handling code, you should raisethis when you encounter an aborted request to make sure the socket isclosed cleanly.

SynchronousOnlyOperation

• exception SynchronousOnlyOperation[source]
• New in Django 3.0:

The SynchronousOnlyOperation exception is raised when code thatis only allowed in synchronous Python code is called from an asynchronouscontext (a thread with a running asynchronous event loop). These parts ofDjango are generally heavily reliant on thread-safety to function and don’twork correctly under coroutines sharing the same thread.

If you are trying to call code that is synchronous-only from anasynchronous thread, then create a synchronous thread and call it in that.You can accomplish this is with asgiref.sync.sync_to_async.

URL Resolver exceptions

URL Resolver exceptions are defined in django.urls.

Resolver404

• exception Resolver404
• The Resolver404 exception is raised byresolve() if the path passed to resolve() doesn’tmap to a view. It’s a subclass of django.http.Http404.

NoReverseMatch

• exception NoReverseMatch
• The NoReverseMatch exception is raised by django.urls when amatching URL in your URLconf cannot be identified based on the parameterssupplied.

Database Exceptions

Database exceptions may be imported from django.db.

Django wraps the standard database exceptions so that your Django code has aguaranteed 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 asthe underlying database exceptions. See PEP 249, the Python Database APISpecification v2.0, for further information.

As per PEP 3134, a cause attribute is set with the original(underlying) database exception, allowing access to any additionalinformation provided.

• exception models.ProtectedError
• Raised to prevent deletion of referenced objects when usingdjango.db.models.PROTECT. models.ProtectedError is a subclassof IntegrityError.

Http Exceptions

Http exceptions may be imported from django.http.

UnreadablePostError

• exception UnreadablePostError
• UnreadablePostError is raised when a user cancels an upload.

Transaction Exceptions

Transaction exceptions are defined in django.db.transaction.

TransactionManagementError

• exception TransactionManagementError
• TransactionManagementError is raised for any and all problemsrelated to database transactions.

Testing Framework Exceptions

Exceptions provided by the django.test package.

RedirectCycleError

• exception client.RedirectCycleError
• RedirectCycleError is raised when the test client detects aloop or an overly long chain of redirects.

Python Exceptions

Django raises built-in Python exceptions when appropriate as well. See thePython documentation for further information on the Built-in Exceptions.