KernelFunctionInvokeError
semantic_kernel.exceptions.KernelFunctionInvokeError
Stack trace
Traceback (most recent call last):
File "app.py", line 42, in <module>
result = kernel.invoke_function("MyFunction", input_data)
File "/usr/local/lib/python3.9/site-packages/semantic_kernel/kernel.py", line 210, in invoke_function
raise KernelFunctionInvokeError(f"Failed to invoke function: {e}")
semantic_kernel.exceptions.KernelFunctionInvokeError: Failed to invoke function: Invalid input format Why it happens
This error occurs when the Semantic Kernel attempts to invoke a registered kernel function but encounters invalid input data, missing required parameters, or internal runtime exceptions. It often happens if the input does not match the expected schema or if the function dependencies are not properly configured.
Detection
Catch KernelFunctionInvokeError exceptions around kernel function calls and log the input and error details to identify mismatches or missing configuration before the app crashes.
Causes & fixes
Input data to the kernel function does not match the expected schema or type
Validate and sanitize input data before invoking the kernel function to ensure it matches the expected format and types.
Required kernel function dependencies or services are not initialized or configured
Ensure all dependencies, such as AI services or connectors, are properly initialized and configured before invoking the function.
The kernel function code raises an unhandled exception during execution
Add error handling inside the kernel function implementation to catch and manage exceptions gracefully.
Incorrect function name or identifier used in the invoke call
Verify the function name string matches exactly the registered kernel function name, including case sensitivity.
Code: broken vs fixed
from semantic_kernel import Kernel
kernel = Kernel()
input_data = {"text": 123} # Invalid input type
result = kernel.invoke_function("MyFunction", input_data) # Raises KernelFunctionInvokeError
print(result)import os
from semantic_kernel import Kernel
from semantic_kernel.exceptions import KernelFunctionInvokeError
os.environ["API_KEY"] = os.environ.get("API_KEY", "your_api_key_here") # Use environment variable for keys
kernel = Kernel()
input_data = {"text": "Valid input string"} # Correct input type
try:
result = kernel.invoke_function("MyFunction", input_data) # Fixed: valid input and error handling
print(result)
except KernelFunctionInvokeError as e:
print(f"Invocation failed: {e}")Workaround
Catch KernelFunctionInvokeError exceptions and parse the raw error message to extract fallback results or retry with corrected inputs.
Prevention
Design kernel functions with strict input validation and initialize all dependencies before invocation; use typed data models to enforce schema compliance.