InvalidArgument
AWS InvalidArgument (Invalid Argument) means one or more request arguments are invalid, missing, or in the wrong format. In Amazon S3, this error returns HTTP 400.
Last reviewed: March 28, 2026|Editorial standard: source-backed technical guidance
What Does Invalid Argument Mean?
The request is rejected at parameter contract validation, so the API action is never executed until argument shape, values, and combinations are corrected.
Common Causes
- -Parameter value format, range, or enum does not satisfy the S3 operation contract.
- -Request includes contradictory header/query combinations for the target API action.
- -Client serializes argument names or types incorrectly for the expected request shape.
- -Migration or feature flags introduce unsupported argument values in one environment.
How to Fix Invalid Argument
- 1Validate the request against the exact operation reference before retrying.
- 2Correct the first invalid field reported, then revalidate dependent fields.
- 3Re-test with a minimal valid request, then add optional parameters incrementally.
- 4Update SDK/client request models when serialization behavior is stale.
Step-by-Step Diagnosis for Invalid Argument
- 1Capture the exact service error message and first failing field context.
- 2Inspect final on-wire payload, headers, and query string values.
- 3Compare request structure against official operation examples.
- 4Add regression tests for malformed inputs, edge values, and invalid combinations.
S3 Operation Contract Review
- -Parse final request against operation-level field contracts (example: unsupported storage class/header combination on PutObject triggers InvalidArgument).
- -Inspect cross-field dependencies in headers and query params (example: invalid range syntax in Range header or incompatible encryption parameter set).
Parameter Encoding and Range Validation
- -Audit serialized parameter encoding and canonicalization (example: URL-encoded metadata key/value differs from expected wire format).
- -Verify enum/range boundaries before dispatch (example: negative or out-of-range part number/expiration value in generated request).
How to Verify the Fix
- -Re-run the request and confirm validation signatures are cleared.
- -Execute contract tests for boundary and malformed request variants.
- -Confirm serialized request shape matches expected operation schema in logs.
How to Prevent Recurrence
- -Generate request validators from typed contracts where available.
- -Add request contract checks and linting gates to CI pipelines.
- -Monitor validation error-rate trends to catch regressions early.
Pro Tip
- -snapshot canonical wire requests in integration tests and diff them per SDK upgrade to catch subtle serialization regressions before production.
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.