Sandbox — LSD is in active testing. All systems operational·payments are test-mode (no real charges).
Overview Use Cases News Docs Tool Store Support Community Get LSD
All docs
Docs/ API Reference/ Errors/ SchemaError
Errors· error

Errors.SchemaError

signals a step's output not matching its declared output_schema

Python
SchemaError(message: str)

Parameters#

name type default description
message str — human-readable description of the schema mismatch

Example#

Python
from lsdtools import SchemaError

try:
    engine.run(clean(t=raw))
except SchemaError as e:
    print("output schema drift:", e)

Raise one from a step when the contract is broken:

Python
raise SchemaError("expected column 'score' (int64), got string")

Notes#

Subclass of ValueError, so except ValueError catches it too. It is raised at run time — when a step's produced Arrow table does not match the output_schema it declared — not at import or load. It marks a contract violation between what a step promised (its declared schema) and what its run() actually returned.

See also#

API: ValidationError · Errors · Tool

Guides: Shape steps · Package anatomy

By LSD Team · Last updated Jul 17, 2026 Ask on Discord View as Markdown