Swagger-UI hangs when expanding operation

Q&A (please complete the following information)

• OS: Windows
• Browser: Chrome
• Version: 141
• Method of installation: webjar
• Swagger-UI version: 5.29.3
• Swagger/OpenAPI version: OpenAPI 3.1

Content & configuration

We have a fairly large OpenAPI file (330 K) generated by springdoc-openapi, which I can't share for confidentiality reasons. The models are generated from complex Java classes that present indirect circular references.

No customization on the Swagger-UI side.

Describe the bug you're encountering

The Swagger-UI page loads normally (although slowly), but when expanding certain operations, the page becomes unresponsive until Chrome offers to kill it.

To reproduce...

Steps to reproduce the behavior:

1. Load the Swagger-UI page
2. Click on an operation to expand it
3. page becomes unresponsive

Expected behavior

Obviously I expect the operation details to be displayed so I can interact with it, or a message that explains that there is an issue with my OpenAPI file, should it be the case.

Screenshots

View of the operation right after clicking on it:

Chrome tasks panel:

Additional context or thoughts

On a suggestion I checked "pause on exception" in the Chrome developer dev tools, I observe that the following two exceptions alternate.

Exception 1:

Exception 2 (with a different value of s each time)

I suspect the problem is related to the circular nature of the model, but I can't change it as it is part of a corporate shared library.

I've seen similar issues raised but not exactly the same, and none that offered a solution.

Thanks for any help.

Start by reproducing the hang in the Swagger-UI page with a large OpenAPI 3.1 document containing indirect circular model references, then inspect the alternating exceptions in Chrome DevTools. Compare expanding an affected operation with a smaller document; done means the operation renders responsively or the UI reports the problematic OpenAPI content instead of becoming unresponsive.