InvalidParameterValueException
AWS InvalidParameterValueException means one of the parameters in the Lambda Invoke request is not valid (HTTP 400).
Last reviewed: March 16, 2026|Editorial standard: source-backed technical guidance
What Does Invalid Parameter Value Exception Mean?
Lambda rejects the invoke request before function execution starts, so no runtime code runs until invoke parameters, qualifier, and payload contracts are corrected.
Common Causes
- -Function name, qualifier, or invocation parameters do not satisfy Lambda API constraints.
- -Payload size/format is incompatible with the selected invocation mode.
- -Alias/version qualifier points to an invalid or unsupported function state.
- -Client sends conflicting headers or request fields for synchronous/asynchronous invocation paths.
How to Fix Invalid Parameter Value Exception
- 1Validate function name, qualifier, and invocation options against Lambda API reference.
- 2Ensure payload encoding and size are valid for the invoke method in use.
- 3Reproduce with a minimal invoke request and add optional parameters incrementally.
- 4Update SDK clients if request model serialization drift is suspected.
Step-by-Step Diagnosis for Invalid Parameter Value Exception
- 1Capture request ID, full validation message, and serialized invoke payload.
- 2Diff failing request against successful invoke calls for the same function and qualifier.
- 3Check payload size limits and content-type assumptions in client code paths.
- 4Validate alias/version existence and health before invocation.
Invoke Contract Validation
- -Audit function identifier and qualifier mapping (example: alias string contains invalid characters or points to a non-published version).
- -Inspect invocation-type-specific payload constraints (example: async invoke path sends payload shape/size valid for sync but not for configured mode).
Serialization and Header Compatibility Checks
- -Parse final JSON bytes and content headers exactly as sent (example: client sends invalid UTF-8 byte sequence that fails Lambda request validation).
- -Compare SDK-generated invoke request with custom transport wrappers (example: proxy layer drops qualifier query string during request forwarding).
How to Verify the Fix
- -Re-run invoke request and confirm InvalidParameterValueException is resolved.
- -Validate function invocation completes with expected status and response payload.
- -Confirm no new parameter-validation failures appear in invocation logs.
How to Prevent Recurrence
- -Use typed invoke request builders shared across all Lambda clients.
- -Add CI validation for function-name/qualifier/payload boundary cases.
- -Monitor Lambda invoke validation failures by client version and deployment.
Pro Tip
- -resolve function ARN and qualifier from deployment outputs at call time instead of static config, then reject invokes when alias/version integrity checks fail.
Decision Support
Compare Guide
HTTP 400 vs 422: Bad Request vs Unprocessable Content
Fix API payload issues faster by using 400 for malformed syntax and 422 for semantic validation failures, so clients correct format before business rules.
Playbook
CORS Error Fix Playbook (Preflight / Origin / Credentials)
Use this playbook to separate browser-enforced cross-origin policy failures from server-side CORS header and route defects and apply strict origin and credential controls safely.
Playbook
Validation Failure Playbook (400 / 422 / INVALID_ARGUMENT)
Use this playbook to separate malformed-request failures from semantic validation failures, then fix request contracts without broad server-side bypasses.
Official References
Provider Context
This guidance is specific to AWS services. Always validate implementation details against official provider documentation before deploying to production.