无法通过Postman调用访问Web API CORE 3.0

我测试的很简单。NET Web API CORE 3.1,并通过以下教程设置简单方法 https://docs.microsoft.com/en-us/aspnet/core/tutorials/first-web-api?view=aspnetcore-3.1&tabs=visual-studio 。我已成功运行Web API,但无法从邮递员处进行调用/

控制器

namespace CoreAPIApplication.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class TodoItemsController : ControllerBase
{
    private readonly TodoContext _context;

    public TodoItemsController(TodoContext context)
    {
        _context = context;
    }

    [HttpGet]
    public async Task<ActionResult<IEnumerable<TodoItem>>> GetTodoItems()
    {
        return await _context.TodoItems.ToListAsync();
    }

    [HttpGet("{id}")]
    public async Task<ActionResult<TodoItem>> GetTodoItem(long id)
    {
        var todoItem = await _context.TodoItems.FindAsync(id);

        if (todoItem == null)
        {
            return NotFound();
        }

        return todoItem;
    }

    [HttpPut("{id}")]
    public async Task<IActionResult> PutTodoItem(long id, TodoItem todoItem)
    {
        if (id != todoItem.Id)
        {
            return BadRequest();
        }

        _context.Entry(todoItem).State = EntityState.Modified;

        try
        {
            await _context.SaveChangesAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            if (!TodoItemExists(id))
            {
                return NotFound();
            }
            else
            {
                throw;
            }
        }

        return NoContent();
    }

    [HttpPost]
    public async Task<ActionResult<TodoItem>> PostTodoItem(TodoItem todoItem)
    {
        _context.TodoItems.Add(todoItem);
        await _context.SaveChangesAsync();

        return CreatedAtAction(nameof(GetTodoItem), new { id = todoItem.Id }, todoItem);
    }

    [HttpDelete("{id}")]
    public async Task<ActionResult<TodoItem>> DeleteTodoItem(long id)
    {
        var todoItem = await _context.TodoItems.FindAsync(id);
        if (todoItem == null)
        {
            return NotFound();
        }

        _context.TodoItems.Remove(todoItem);
        await _context.SaveChangesAsync();

        return todoItem;
    }

    private bool TodoItemExists(long id)
    {
        return _context.TodoItems.Any(e => e.Id == id);
    }
 }
}

我尝试了邮递员设置中启用SSL证书和不启用SSL证书,但仍然没有结果