Note: Python 2.7 has reached end of support on January 31, 2024. Your existing Python 2.7 applications will continue to run and receive traffic. However, App Engine might block re-deployment of applications that use runtimes after their end of support date. We recommend that you migrate to the latest supported version of Python.

Exceptions

In addition to the DB datastore exceptions, the NDB datastore provides the following exception classes:

exception ComputedPropertyError(): Raised when attempting to set a value to or delete a computed property.
exception InvalidPropertyError(): Raised when a property is not applicable to a given use. For example, a property must exist and be indexed to be used in a query's projection or group by clause.
exception ReadonlyPropertyError(): Raised when attempting to set a property value that is read-only.
exception UnprojectedPropertyError(): Raised when getting a property value that's not in the projection.