invoke-ai/InvokeAI · info · HTTPException

str(e) (ValueError, relationship already exists)

Error message

str(e) (ValueError, relationship already exists)

What it means

HTTP 409 raised when the model relationships service throws ValueError because the exact bidirectional relationship between the two keys already exists. Since relationships are unique unordered pairs, adding the same pair twice collides.

Source

Thrown at invokeai/app/api/routers/model_relationships.py:132

) -> None:
    """
    Add a relationship between two models.

    Relationships are bidirectional and will be accessible from both models.

    - Raises 400 if keys are invalid or identical.
    - Raises 409 if the relationship already exists.
    """
    if req.model_key_1 == req.model_key_2:
        raise HTTPException(status_code=400, detail="Cannot relate a model to itself.")

    try:
        ApiDependencies.invoker.services.model_relationships.add_model_relationship(
            req.model_key_1,
            req.model_key_2,
        )
    except ValueError as e:
        raise HTTPException(status_code=409, detail=str(e))


@model_relationships_router.delete(
    "/",
    status_code=status.HTTP_204_NO_CONTENT,
    responses={
        204: {"description": "The relationship was successfully removed"},
        400: {"description": "Invalid model keys or self-referential relationship"},
        404: {"description": "The relationship does not exist"},
        422: {"description": "Validation error"},
        500: {"description": "Internal server error"},
    },
    summary="Remove Model Relationship",
    description="Removes a **bidirectional** relationship between two models. The relationship must already exist.",
)
def remove_model_relationship(
    current_user: AdminUserOrDefault,
    req: ModelRelationshipCreateRequest = Body(..., description="The model keys to disconnect"),

View on GitHub (pinned to 0b6a024f2f)

Solutions

1. Treat 409 as success (the relationship exists) and continue
2. Before adding, call GET related-models for one key and skip pairs already present
3. Deduplicate the input pair list and use 'add or ignore' logic in scripts
4. Wrap the call so ValueError/409 is swallowed but other errors propagate

Example fix

// before
await api.addRelationship({ model_key_1: a, model_key_2: b });
// after
try {
  await api.addRelationship({ model_key_1: a, model_key_2: b });
} catch (e) {
  if (e.status !== 409) throw e; // already related — fine
}

const existing = new Set(await api.getRelatedModels(key1));
if (existing.has(key2)) {
  console.log('already related');
} else {
  await api.addRelationship({ model_key_1: key1, model_key_2: key2 });
}

try {
  await api.addRelationship({ model_key_1: a, model_key_2: b });
} catch (e) {
  if (e.status === 409) return; // idempotent no-op
  throw e;
}

When it happens

Trigger: POST /api/v1/models/relationships with a (key1, key2) pair that was already related in either order; duplicate form submissions; scripts that don't check for existing relationships before adding.

Common situations: Re-running an idempotency-breaking sync script; double-clicking the 'relate' button; importing a relationships list that contains duplicates.

Related errors

• str(e) (Exception during conversion)
• Cannot relate a model to itself.
• Cannot unlink a model from itself.
• str(e) (ValueError, relationship not found)
• str(e)

AI-assisted analysis of invoke-ai/InvokeAI@0b6a024f2f (2026-08-29). Data as JSON: /api/errors/b2e9ee3ac32116a6. Report an issue: GitHub.