@Marvin is the bug fixed where a flow with default parameters would cause errors?

There are a couple of issues related to default parameters in Prefect, but none of the issues specifically mention a general error caused by flows with default parameters. Here are two relevant issues: 1. Default Parameter Type Cannot Be Set to "None": This issue describes a problem where setting default values for parameters to

None

is not adhered to, causing flow runs to fail with validation errors. More details are available here. 2. Boolean Flow Parameter Defaults to False in UI: This issue highlights a problem where boolean parameters default to

False

in the UI when no default is given in the code. More details can be found here. If your issue is related to these, it might still be unresolved. If not, you might consider providing more specific details or checking the Prefect GitHub issues page for updates.

@Marvin I believe this was a more recent issue in prefect 3

I couldn't find a specific recent issue in Prefect 3.x that directly mentions a bug with flows using default parameters causing errors. However, there are a couple of related issues: 1. Default Parameter Type Cannot Be Set to "None": This issue notes that setting default values to

None

isn't adhered to, causing validation errors during flow runs. You can read more about it here. 2. Boolean Flow Parameter Defaults to False in UI: This issue describes a problem where boolean parameters default to

False

in the UI when no default is provided in the code. More details are available here. If your issue is distinct from these, it may not be widely reported or documented yet. You might want to check the Prefect GitHub issues page for any updates or consider reporting the issue if it persists.

@Marvin I get the following error message: Parameters: {'run_load': [], 'debug': 0} 140732.719 | ERROR | prefect.engine - Validation of flow parameters failed with error: Flow run received invalid parameters: - run_single_dwh_load: Input should be a valid dictionary

The error message you're encountering, "Validation of flow parameters failed with error: Flow run received invalid parameters," suggests that the parameters provided to the flow do not match the expected types or structure defined in the flow's signature. ### Key Points: 1. Type Validation: Prefect validates parameters against the flow's type annotations. If a parameter is expected to be a dictionary and receives a different type (like a list or integer), a

ParameterTypeError

will be raised. 2. Keyword Arguments: When providing parameters to a flow, especially through the Prefect API, you must use keyword arguments. Positional arguments are not accepted. 3. Flow Parameter Requirements: Ensure that all required parameters are provided and that optional parameters have appropriate default values. ### Solution: - Check Parameter Types: Verify that the parameters

run_load

and

debug

are being passed in the expected format. If

run_single_dwh_load

is expected to be a dictionary, ensure that it is not an empty list or another type. - Use Keyword Arguments: Ensure that you are passing parameters as keyword arguments when initiating a flow run. For more detailed information on handling parameters in Prefect 3.x, you can refer to the Prefect documentation on writing flows. If this issue persists, consider revisiting the flow's function signature to ensure all parameters are correctly defined and annotated.