RangeError: Maximum call stack size exceeded

Q&A (please complete the following information)

• OS: Win7
• Browser: Chrome
• Version: 91.0.4472
• Project Type - ASP.NET 5.0
• Method of installation: Nuget Manager in Visual Studio 2019
• Swagger-UI version: 6.1.4
• Swagger/OpenAPI version: OpenApi 3.0.1

Content & configuration

Example Swagger/OpenAPI definition:

{
  "openapi": "3.0.1",
  "info": {
    "title": "MyAPI",
    "version": "v1"
  },
  "paths": {
    "/api/packages": {
      "get": {
        "tags": [
          "Packages"
        ],
        "responses": {
          "200": {
            "description": "Success",
            "content": {
              "text/plain": {
                "schema": {
                  "type": "array",
                  "items": {
                    "$ref": "#/components/schemas/Package"
                  }
                }
              },
              "application/json": {
                "schema": {
                  "type": "array",
                  "items": {
                    "$ref": "#/components/schemas/Package"
                  }
                }
              },
              "text/json": {
                "schema": {
                  "type": "array",
                  "items": {
                    "$ref": "#/components/schemas/Package"
                  }
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "FileData": {
        "type": "object",
        "properties": {
          "name": {
            "type": "string",
            "nullable": true
          },
          "path": {
            "type": "array",
            "items": {
              "type": "string"
            },
            "nullable": true
          },
          "size": {
            "type": "integer",
            "format": "int64"
          },
          "hash": {
            "type": "string",
            "nullable": true
          },
          "locator": {
            "type": "array",
            "items": {
              "type": "string"
            },
            "nullable": true,
            "readOnly": true
          },
          "isCompressed": {
            "type": "boolean",
            "readOnly": true
          }
        },
        "additionalProperties": false
      },
      "Package": {
        "type": "object",
        "properties": {
          "id": {
            "type": "string",
            "nullable": true
          },
          "name": {
            "type": "string",
            "nullable": true
          },
          "version": {
            "type": "string",
            "nullable": true
          },
          "compressedFile": {
            "$ref": "#/components/schemas/FileData"
          },
          "files": {
            "type": "array",
            "items": {
              "$ref": "#/components/schemas/FileData"
            },
            "nullable": true
          },
          "fileServerUrl": {
            "type": "string",
            "nullable": true
          },
          "timestamp": {
            "type": "string",
            "nullable": true
          }
        },
        "additionalProperties": false
      }
    }
  }
}

Swagger-UI configuration options:

public void ConfigureServices(IServiceCollection services)
{
    services.AddSwaggerGen(c => c.SwaggerDoc("v1", new OpenApiInfo { Title = "MyAPI", Version = "v1" });
}

public void Configure(IApplicationBuilder app)
{
    app.UseSwagger();
    app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "MyAPI v1"));
}

Describe the bug you're encountering

We are upgrading from ASP.NET 4.72 to 5.0 and had a GET end point which returns collection of a schema. The older code works with Swashbuckle.AspNetCore v4.0.1 and the latest code has v6.1.4.

The endpoint returns json of 542,580 characters in older version & in latest version fails with message RangeError: Maximum call stack size exceeded. The endpoint works from postman in both versions, its in swagger UI that this happens. Also, UI becomes unresponsive and hangs. In logs, the .Net logs says the data is returns in couple of seconds.

2021-06-29 15:50:28.2021 INFO [70] [Microsoft.AspNetCore.Hosting.Diagnostics] Request starting HTTP/1.1 GET http://myserver:12912/api/packages - - 
2021-06-29 15:50:28.2021 INFO [70] [Microsoft.AspNetCore.Routing.EndpointMiddleware] Executing endpoint 'MyAPI.PackagesController.Get (MyAPI)' 
2021-06-29 15:50:28.2021 INFO [70] [Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker] Route matched with {action = "Get", controller = "Packages"}. Executing controller action with signature System.Threading.Tasks.Task`1[System.Collections.Generic.IEnumerable`1[MyAPI.Package]] Get() on controller MyAPI.PackagesController (MyAPI). 
2021-06-29 15:50:28.5674 INFO [70] [Microsoft.AspNetCore.Mvc.Infrastructure.ObjectResultExecutor] Executing ObjectResult, writing value of type 'System.Collections.Generic.List`1[[MyAPI.Package, MyAPI, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null]]'. 
2021-06-29 15:50:28.9621 INFO [65] [Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker] Executed action MyAPI.PackagesController.Get (MyAPI) in 757.9003ms 
2021-06-29 15:50:28.9621 INFO [65] [Microsoft.AspNetCore.Routing.EndpointMiddleware] Executed endpoint 'MyAPI.PackagesController.Get (MyAPI)' 
2021-06-29 15:50:28.9621 INFO [65] [Microsoft.AspNetCore.Hosting.Diagnostics] Request finished HTTP/1.1 GET http://myserver:12912/api/packages - - - 200 5042580 application/json;+charset=utf-8 760.1613ms 

To reproduce...

Steps to reproduce the behavior:
In the latest version, hit an api in swagger UI which return a heavy schema json returning around 0.5 million characters.

Expected behavior

The endpoint should not fail to return results and should be backward compatible with previous versions.

Screenshots

New version

Older Version

Postman

Start by reproducing the issue in Swagger UI with the provided ASP.NET endpoint and its roughly 5 MB JSON response in Chrome. Trace the response-rendering entry point that produces the RangeError or UI hang; done means the endpoint renders without a stack overflow or becoming unresponsive, while preserving the existing response behavior.