prefect.exceptions

Prefect-specific exceptions.

Functions

exception_traceback ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L48" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

exception_traceback(exc: Exception) -> str

Convert an exception to a printable string with a traceback

Classes

PrefectException ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L56" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Base exception type for Prefect errors.

CrashedRun ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L62" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when the result from a crashed run is retrieved.

This occurs when a string is attached to the state instead of an exception or if the state's data is null.

FailedRun ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L71" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when the result from a failed run is retrieved and an exception is not attached.

This occurs when a string is attached to the state instead of an exception or if the state's data is null.

CancelledRun ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L81" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when the result from a cancelled run is retrieved and an exception is not attached.

This occurs when a string is attached to the state instead of an exception or if the state's data is null.

PausedRun ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L91" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when the result from a paused run is retrieved.

UnfinishedRun ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L103" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when the result from a run that is not finished is retrieved.

For example, if a run is in a SCHEDULED, PENDING, CANCELLING, or RUNNING state.

MissingFlowError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L111" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a given flow name is not found in the expected script.

UnspecifiedFlowError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L117" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when multiple flows are found in the expected script and no name is given.

MissingResult ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L123" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a result is missing from a state; often when result persistence is disabled and the state is retrieved from the API.

ScriptError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L130" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a script errors during evaluation while attempting to load data

ParameterTypeError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L153" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a parameter does not pass Pydantic type validation.

Methods:

from_validation_error ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L162" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

from_validation_error(cls, exc: ValidationError) -> Self

ParameterBindError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L171" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when args and kwargs cannot be converted to parameters.

Methods:

from_bind_failure ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L180" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

from_bind_failure(cls, fn: Callable[..., Any], exc: TypeError, call_args: tuple[Any, ...], call_kwargs: dict[str, Any]) -> Self

SignatureMismatchError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L196" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when parameters passed to a function do not match its signature.

Methods:

from_bad_params ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L203" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

from_bad_params(cls, expected_params: list[str], provided_params: list[str]) -> Self

ObjectNotFound ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L213" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when the client receives a 404 (not found) from the API.

ObjectAlreadyExists ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L233" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when the client receives a 409 (conflict) from the API.

ObjectLimitReached ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L243" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when the client receives a 403 (forbidden) from the API due to reaching an object limit (e.g. maximum number of deployments).

ObjectUnsupported ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L253" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when the client receives a 403 (forbidden) from the API due to an unsupported object (i.e. requires a specific Prefect Cloud tier).

UpstreamTaskError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L263" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a task relies on the result of another task but that task is not 'COMPLETE'

MissingContextError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L270" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a method is called that requires a task or flow run context to be active but one cannot be found.

MissingProfileError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L277" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a profile name does not exist.

ReservedArgumentError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L283" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a function used with Prefect has an argument with a name that is reserved for a Prefect feature

InvalidNameError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L290" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a name contains characters that are not permitted.

PrefectSignal ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L296" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Base type for signal-like exceptions that should never be caught by users.

Abort ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L302" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when the API sends an 'ABORT' instruction during state proposal.

Indicates that the run should exit immediately.

Pause ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L310" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a flow run is PAUSED and needs to exit for resubmission.

ExternalSignal ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L322" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Base type for external signal-like exceptions that should never be caught by users.

TerminationSignal ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L328" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a flow run receives a termination signal.

PrefectHTTPStatusError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L337" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when client receives a Response that contains an HTTPStatusError.

Used to include API error details in the error messages that the client provides users.

Methods:

from_httpx_error ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L345" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

from_httpx_error(cls: type[Self], httpx_error: HTTPStatusError) -> Self

Generate a PrefectHTTPStatusError from an httpx.HTTPStatusError.

MappingLengthMismatch ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L368" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when attempting to call Task.map with arguments of different lengths.

MappingMissingIterable ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L374" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when attempting to call Task.map with all static arguments

BlockMissingCapabilities ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L380" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a block does not have required capabilities for a given operation.

ProtectedBlockError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L386" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when an operation is prevented due to block protection.

InvalidRepositoryURLError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L392" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when an incorrect URL is provided to a GitHub filesystem block.

InfrastructureError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L396" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

A base class for exceptions related to infrastructure blocks

InfrastructureNotFound ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L402" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when infrastructure is missing, likely because it has exited or been deleted.

InfrastructureNotAvailable ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L409" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when infrastructure is not accessible from the current machine. For example, if a process was spawned on another machine it cannot be managed.

NotPausedError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L416" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when attempting to unpause a run that isn't paused.

FlowPauseTimeout ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L420" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a flow pause times out

FlowRunWaitTimeout ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L424" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a flow run takes longer than a given timeout

PrefectImportError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L428" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

An error raised when a Prefect object cannot be imported due to a move or removal.

SerializationError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L437" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when an object cannot be serialized.

ConfigurationError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L443" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a configuration is invalid.

EventTooLarge ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L449" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when an event exceeds the configured maximum size.

ProfileSettingsValidationError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L460" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when a profile settings are invalid.

HashError ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/exceptions.py#L469" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Raised when hashing objects fails