Circular reference in schema leads to Could not resolve reference: undefined undefined

Q&A (please complete the following information)

• OS: Alpine Linux
• Browser: Vivaldi
• Version: 2.9
• Method of installation: docker
• Swagger-UI version: actually unknown, should be latest
• Swagger/OpenAPI version: OpenAPI 3.0

Content & configuration

Example Swagger/OpenAPI definition:

openapi: "3.0.0"
info:
  title: "Test API For Self Reference"
  version: "1.0"


paths:
  /greeting:
    get:
      tags:
        - Client
      description: 'Get the current client session identifier.'
      responses:
        200: 
          description: OK
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Person'
        
components:
  schemas:
    Person:
      type: object
      required:
        - name
        - age
      properties:
        name:
         type: string
         example: 'John Doe'
        age:
          type: integer
          example: 42
        parent:
          $ref: '#/components/schemas/Person'
        brother:
          $ref: '#/components/schemas/Person'

Swagger-UI configuration options: Where do I find it?

Describe the bug you’re encountering

When expanding the Person schema, Swagger-UI displays this error on top of the page: Resolver error at components.schemas.Person.properties.parent.$ref Could not resolve reference: undefined undefined

To reproduce…

Steps to reproduce the behavior:

1. Scroll down to ‘schemas’
2. Click on ‘Person’ to expand it
3. Scroll up to the top of the page
4. See error

Expected behavior

No error should occur.

[hnthu]

I have met the same issue for using 3.25.2. I have a quick check and figure out the issue happened from 3.22.3 Have check on editor.swagger.io

it’s empty instead of throwing a warning on the top of the page.

[bligny]

The issue is still there (5 months later). Any fix foreseen ?