microsoft/semantic-kernel · error · FunctionExecutionException

Error while registering Rest function {plugin_name}.{operati

Error message

Error while registering Rest function {plugin_name}.{operation.id}: {ex}

What it means

A broad catch around `_create_function_from_operation(...)` and `operation.freeze()`: any exception while turning a parsed `RestApiOperation` into a `KernelFunction` is wrapped in `FunctionExecutionException` with the plugin name, operation id, and the original cause. The error is logged before being re-raised, so the inner exception text is available in logs.

Source

Thrown at python/semantic_kernel/connectors/openapi_plugin/openapi_manager.py:106

        else None,
    )

    functions = []
    for operation in operations.values():
        try:
            kernel_function = _create_function_from_operation(
                openapi_runner,
                operation,
                plugin_name,
                execution_parameters=execution_settings,
                security=global_security_requirements,
            )
            functions.append(kernel_function)
            operation.freeze()
        except Exception as ex:
            error_msg = f"Error while registering Rest function {plugin_name}.{operation.id}: {ex}"
            logger.error(error_msg)
            raise FunctionExecutionException(error_msg) from ex

    return functions


@experimental
def _create_function_from_operation(
    runner: OpenApiRunner,
    operation: RestApiOperation,
    plugin_name: str | None = None,
    execution_parameters: "OpenAPIFunctionExecutionParameters | None" = None,
    document_uri: str | None = None,
    security: list[RestApiSecurityRequirement] | None = None,
) -> KernelFunctionFromMethod:
    logger.info(f"Registering OpenAPI operation: {plugin_name}.{operation.id}")

    rest_operation_params: list[RestApiParameter] = operation.get_parameters(
        operation=operation,
        add_payload_params_from_metadata=getattr(execution_parameters, "enable_dynamic_payload", True),

View on GitHub (pinned to c028a0c7dc)

Solutions

1. Read the `{ex}` portion / check logs (`logger.error`) to find the root cause — this error is only a wrapper.
2. Isolate the failing `operationId` from the message and inspect that operation in the spec.
3. Fix or remove the offending operation (correct its schema/parameters), then re-register.
4. Use operation include/exclude filters to skip the broken operation while it is being fixed.

Example fix

# before: registration aborts with the wrapped message
kernel.add_openapi_plugin(plugin_name="x", openapi_document_path="/specs/x.yaml")
# -> 'Error while registering Rest function x.createUser: <root cause>'

# after: exclude the broken op until fixed
kernel.add_openapi_plugin(
    plugin_name="x",
    openapi_document_path="/specs/x.yaml",
    execution_parameters=OpenAPIFunctionExecutionParameters(
        exclude_operations=["createUser"],
    ),
)

# validate each operation in the spec before registration
def validate_operations(spec) -> None:
    for path, methods in spec.get("paths", {}).items():
        for method, details in methods.items():
            assert "operationId" in details, f"{method} {path} missing operationId"
            for p in details.get("parameters", []):
                assert p.get("in"), f"{method} {path} param {p.get('name')} missing 'in'"
                assert "content" not in p, f"{method} {path} param {p.get('name')} uses 'content'"

validate_operations(spec)

from semantic_kernel.exceptions import FunctionExecutionException

try:
    functions = kernel.add_openapi_plugin(plugin_name="x", openapi_parsed_spec=spec)
except FunctionExecutionException as e:
    msg = str(e)
    if "Error while registering Rest function" in msg:
        op_id = msg.split(".")[-1].strip(": ")
        logger.error("Failing operation likely: %s; root cause in logs", op_id)
    raise

When it happens

Trigger: Any failure during per-operation function construction — e.g. a parameter schema that breaks `KernelParameterMetadata`, a payload build failure, a frozen-state mutation, or a freeze-time exception — surfaces here as a wrapped error. The `operation.id` in the message tells you which operation failed.

Common situations: A single malformed operation in an otherwise-valid spec; an operation whose schema uses constructs the plugin does not support; version skew between the spec and the connector; partial registration where some operations succeed before one fails.

Related errors

• Agent type '{recipient.type}' does not exist.
• Agent with type {type} already exists.
• Factory registered using the wrong type.
• Agent with name {agent_id.type} not found.
• Agent with name {id.type} not found.

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/054ab50064994608. Report an issue: GitHub.