Swagger failed to load api definition.

Failed to load API definition is displayed on the Swagger Generation page

Environment

Description

"Failed to load API definition." message is displayed on the Swagger Generation page.

There may also be a short error on the page about being unable to fetch swagger.json.

Error Message

• Error message on client-side:

Fetch error

response status is 500 https://localhost:{port}/swagger/v1/swagger.json

• Server-side exception:

An unhandled exception has occurred while executing the request.
      Swashbuckle.AspNetCore.SwaggerGen.SwaggerGeneratorException: Conflicting method/path combination "GET api/ReportDesignerControllerBase" for actions - Telerik.WebReportDesigner.Services.Controllers.ReportDesignerControllerBase.GetDesignerResource (Telerik.WebReportDesigner.Services),Telerik.WebReportDesigner.Services.Controllers.ReportDesignerControllerBase.GetResource (Telerik.WebReportDesigner.Services). Actions require a unique method/path combination for Swagger/OpenAPI 3.0. Use ConflictingActionsResolver as a workaround
         at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperations(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
         at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GeneratePaths(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
         at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwagger(String documentName, String host, String basePath)
         at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
         at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Cause

There is a confliction method/path in ReportDesignerController. Swagger requires actions to have unique methods/paths.

Solution

• For .NET Core 3.1 and .NET 5, configure the Swagger Generation in Startup.cs:

 public void ConfigureServices(IServiceCollection services)
        {
        ...
            services.AddSwaggerGen(c => {
                c.ResolveConflictingActions(apiDescriptions => apiDescriptions.First());
                c.IgnoreObsoleteActions();
                c.IgnoreObsoleteProperties();
                c.CustomSchemaIds(type => type.FullName);
                });
                ...
        }

• For .NET 6, configure the Swagger Generation in Program.cs

builder.Services.AddSwaggerGen(c => {
    c.ResolveConflictingActions(apiDescriptions => apiDescriptions.First());
    c.IgnoreObsoleteActions();
    c.IgnoreObsoleteProperties();
    c.CustomSchemaIds(type => type.FullName);
});

The Swagger user interface (UI) is an HTML/JS web application that can be hosted on simple web servers such as Apache, Microsoft Internet Information Services (IIS), or Apache Tomcat. The Swagger UI provides a sample request response that helps to integrate  AR System server with the REST service.

This topic describes the most common issues that might occur while using the Swagger UI.

Symptoms

• Pages are not displayed for the specified Jetty URLs.
• Pages are not displayed for the specified Swagger URLs.
• One of the following errors is displayed:
  Failed to load API definition on Swagger UI
  Or
  Possible cross-origin (CORS) issue
• The API definition is not provided in the Swagger UI.

Scope

Swagger, being a third-party tool, does not affect other areas. If the Jetty server doesn't respond, the Swagger UI and other integrations that use the Jetty server do not work.

Resolution

Perform the following steps to troubleshoot an issue:

Step	Task	Description
1	Ensure that the Jetty server is running	By default, the Jetty server runs on port 8008 and port 8443. For more information, see the following documents: Configuring the REST API by using SSL certificates Troubleshooting the REST API Knowledge article How to test if a webserver is responding to requests
2	Enable the Swagger UI	Follow the instructions in the Using the REST API with Swagger topic. Ensure that you can access the Swagger UI through a URL. For example, http://TOMCAT:8080/swagger-ui/index.html Do not use the file:// protocol to access the Swagger UI.
3	Remove the Cross-Origin Resource Sharing (CORS) restrictions	If the following error occurs in the Swagger UI, remove the CORS restrictions on the Jetty server: Possible cross-origin (CORS) issue? The URL origin (http://[Not_localhost]:8008) does not match the page (http://localhost:8080/). For information about removing CORS restrictions, see the knowledge article How to avoid RSSO from filtering REST requests. If the error prevails, Remedy SSO might be intercepting the requests.
4	Configure the Swagger UI to load AR System definitions	The Swagger UI shows a blank page or the following error: No API definition provided This error can occur in the following circumstances: Syntax errors in the index.html file, located in /swagger/dist/ folder. The variable URL does not have adequate content. For more information about configuring the Swagger UI, see the knowledge article How to configure swagger UI to load Remedy REST definitions.
5	Using swagger	You cannot use the Swagger UI to send attachments. For more information, see the knowledge article How to send Attachments into Remedy REST API.

After you determine a specific symptom or error message, use the following table to identify the solution:

Symptom	Location	Action
	AR System server version 19.08	Enable CORS settings for the Swagger UI. For more information, see the knowledge article REMEDY REST API - CORS setup for Swagger UI.
You don't get a response when you access a URL pointing to a REST API. For example, http://server:port/api/arsys/v1.0/swagger/ars-jwt.json	AR System server version 9.x and later	Enable debug logs on the Jetty server and create a support case. For instructions on how to enable Jetty logs, see the knowledge article How to turn logging on for REST API problems
The browser receives no response when accessing the Swagger UI. For example, http://localhost:8080/arsys/shared/swagger/index.html	Any web server hosting html or javascript	Ensure that the following conditions are met: The HTTP server is up and running. The HTTP server can host the HTML file. The browser can run javascript files. If the issue persists, document the steps followed to publish the Swagger UI web pages and create a support case. For more information, see Using the REST API with Swagger.

Was this page helpful? Yes No Submitting... Thank you