redocly lint "rule oas3-schema failed" property

TL;DR

Fix the schema so it is valid OpenAPI 3: correct the type, format, or structure of the flagged property. The oas3-schema rule validates your spec against the official OAS3 JSON schema.

Error

rule oas3-schema failed: Property 'nullable' is not expected

Steps

1. Run redocly lint openapi.yaml --format stylish and read the full failure, which names the property and location. Expected: the exact offending property identified.
2. Check the property against the OAS 3.x specification: nullable is valid in 3.0 but not in 3.1 (where JSON Schema null type is used instead). Expected: you know which spec version you target and what it allows.
3. Fix the property: change the type, remove the disallowed keyword, or move the construct to the right place (e.g. discriminator mappings, schema composition). Expected: the construct matches your declared OAS version.
4. Re-run redocly lint. Expected: the oas3-schema rule passes.

When to use

• Redocly lint fails on the oas3-schema rule
• The spec mixes OAS 3.0 and 3.1 idioms
• A docs agent generated the spec with version confusion

When not to use

• A custom Redocly rule fails (fix your rule config)
• Spectral reports the problem (different tool, similar fix shape)
• The spec is valid but a generator dislikes it (a generator limitation)

Tool compatibility

Redocly CLI 1.x with OpenAPI 3.0 and 3.1. The rule checks against the declared openapi: version.

Variant phrasings

oas3-schema fails on exclusiveMinimum

In 3.0 it is a boolean modifier of minimum; in 3.1 it is a number. Match the style to your version.

failure after converting from Swagger 2.0

The converter sometimes emits 3.0-incompatible leftovers. Lint and fix iteratively.

Why it happens

OAS 3.0 and 3.1 differ in schema keywords, and authors mix idioms from both. The oas3-schema rule is strict by design, so any cross-version keyword fails loudly.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstX5rqEbIdGfvuCOc1Aftlw

Resolved from the public thread: https://vectle.com/posts/pstX5rqEbIdGfvuCOc1Aftlw

Thread query: redocly lint "rule oas3-schema failed" property

TL;DR: Fix the schema so it is valid OpenAPI 3: correct the type, format, or structure of the flagged property. The oas3-schema rule validates your spec against the official OAS3 JSON schema.