Problem Statement
I am encountering a 500 error with the message “Failed to load API definition” when I build and run my .NET 8 project. The error appears in the UI, indicating a problem with loading the API documentation.

Code Example
Here is a sample of the code from my ReportsController:

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Authorization;

namespace DMSSWE.SECURITY.WEBAPI.Controllers
{
    [ApiController]
    [Route("api/[controller]")]
    [Authorize]
    public class ReportsController : ControllerBase
    {
        private readonly IReports _bl;
        private readonly string[] connectionValues = new string[2];

        public ReportsController()
        {
            connectionValues[0] = GlobalData.ConnectionString;
            connectionValues[1] = GlobalData.ConnectionType.ToString();

            switch (Convert.ToInt32(connectionValues[1]))
            {
                case (int)ConnectionType.MSSQL:
                    _bl = new ReportsSQL();
                    break;

                case (int)ConnectionType.ORACLE:
                    _bl = new ReportsORA();
                    break;

                case (int)ConnectionType.POSTGRESQL:
                    _bl = new ReportsPGSQL();
                    break;


                default:
                    break;
            }
        }        
      
        [HttpPost]
        [Route("PostReportDetails")]
        public IActionResult PostReportDetails([FromBody] IREPORTSDTO reports)
        {
            try
            {
                bool result = _bl.PostReportDetails(connectionValues, reports);
                return this.Ok(result);
            }
            catch (Exception)
            {
                return this.StatusCode(StatusCodes.Status500InternalServerError);
            }
        }
    }
}

Details
Framework: .NET 8
Issue: UI displays a 500 error with the message “Failed to load API definition” after running the project.
Objective: Understand the cause of the error and find a way to resolve it.
What I’ve Tried

• Checking Connection Strings: Verified that the GlobalData.ConnectionString and GlobalData.ConnectionType are correctly set.
• Dependency Injection: Ensured that the dependency injection is properly configured in Program.cs.
• Authorization: Verified that the [Authorize] attribute is correctly used and configured.

Any insights or suggestions on how to resolve this issue would be greatly appreciated. Thank you in advance for your help!