Use explicit, JSON-compatible YAML values
Aliases, merge keys, tags, directives, and non-string keys are outside this parser’s subset.
Match the finding
These titles and messages come from this local checker. They are not AWS service error quotes.
YAML aliases and merge expansion are disabled. Use explicit values instead.YAML merge keys are disabled. Use explicit values instead.Explicit YAML tags are not supported.YAML mapping keys must be strings. Quote numeric status codes such as "200".
Cause and scope
The local checker accepts a restricted YAML 1.2 input subset. It does not expand aliases, evaluate explicit tags, or apply merge keys and directives. These restrictions are tool safety boundaries, not a claim that all such YAML is invalid.
What to do
Use a trusted local workflow to create explicit JSON-compatible values, compare them with the intended source, and quote mapping keys such as response codes.
- For aliases or merges, copy the intended explicit values while checking overrides and expansion size.
- For tags or directives, determine the intended scalar and schema interpretation before rewriting.
- Use string mapping keys and ordinary JSON-compatible scalar values, then validate the rewritten document.
Response fragment: quote numeric-looking keys
responses:
'200':
description: OK
'404':
description: Not foundThese response codes are string keys. The checker rejects an unquoted numeric key rather than silently converting it.
Avoid a misleading fix
Do not remove tags, directives, or aliases without first checking their meaning. Do not use repeated references to create cyclic or unexpectedly expanded data.
Check your complete file locally
Choose one OpenAPI 3.0 JSON or YAML file, diagnose the findings, and review any eligible security-copy preview before downloading. No file upload or account is needed.
Related findings
Sources and scope
Scope: this local checker, API Gateway REST APIs, and OpenAPI 3.0. Guidance reviewed 4 October 2026. A passing check does not guarantee import or runtime behavior.