invoke-ai/InvokeAI · error · ValueError

stop must be greater than start

Error message

stop must be greater than start

What it means

A Pydantic field_validator on the RangeInvocation enforces that stop is strictly greater than start whenever start is present in the validated data. This runs at input validation time, before invoke().

Source

Thrown at invokeai/app/invocations/collections.py:25

from invokeai.app.invocations.baseinvocation import BaseInvocation, invocation
from invokeai.app.invocations.fields import InputField
from invokeai.app.invocations.primitives import IntegerCollectionOutput
from invokeai.app.services.shared.invocation_context import InvocationContext
from invokeai.app.util.misc import SEED_MAX


@invocation("range", title="Integer Range", tags=["collection", "integer", "range"], category="batch", version="1.0.0")
class RangeInvocation(BaseInvocation):
    """Creates a range of numbers from start to stop with step"""

    start: int = InputField(default=0, description="The start of the range")
    stop: int = InputField(default=10, description="The stop of the range")
    step: int = InputField(default=1, description="The step of the range")

    @field_validator("stop")
    def stop_gt_start(cls, v: int, info: ValidationInfo):
        if "start" in info.data and v <= info.data["start"]:
            raise ValueError("stop must be greater than start")
        return v

    def invoke(self, context: InvocationContext) -> IntegerCollectionOutput:
        return IntegerCollectionOutput(collection=list(range(self.start, self.stop, self.step)))


@invocation(
    "range_of_size",
    title="Integer Range of Size",
    tags=["collection", "integer", "size", "range"],
    category="batch",
    version="1.0.0",
)
class RangeOfSizeInvocation(BaseInvocation):
    """Creates a range from start to start + (size * step) incremented by step"""

    start: int = InputField(default=0, description="The start of the range")
    size: int = InputField(default=1, gt=0, description="The number of values")

View on GitHub (pinned to 0b6a024f2f)

Solutions

1. Swap the values so stop > start.
2. If a descending range is intended, this node does not support it via validation — build the collection in code instead.
3. Add UI/client-side validation so start/stop are checked before submitting the graph.

Example fix

// before
RangeInvocation(start=10, stop=1, step=-1)
// after
RangeInvocation(start=1, stop=10, step=1)  # then reverse the collection if needed

if stop <= start:
    raise ValueError(f"stop ({stop}) must be greater than start ({start})")

try:
    node = RangeInvocation(start=start, stop=stop, step=step)
except ValidationError as e:
    log_and_correct_range_bounds(e)

When it happens

Trigger: Creating/queueing a Range node with stop <= start (e.g. start=10, stop=10, or start=5, stop=2). Note a reversed range like start=10, stop=1 with step=-1 also fails because the check requires strict inequality.

Common situations: Computing start/stop from variables where a swap accidentally reversed them; default edits in the UI; users expecting Python-style descending range() with negative step.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• cfg_scale must be greater than 1
• Face IDs must be a comma-separated list of integers (e.g. "1
• cfg_scale values must be finite.
• shift must be finite.
• Cannot divide by zero

AI-assisted analysis of invoke-ai/InvokeAI@0b6a024f2f (2026-08-29). Data as JSON: /api/errors/844fe3be064e0d58. Report an issue: GitHub.