ASP.NET Core MVC登录遇HTTP ERROR 400：无法匹配[HttpPost]方法问题

问题现象 #

原本正常的ASP.NET Core MVC账户登录功能，在创建Identity自定义_PartialView后出现错误：

此页面无法正常工作
若问题持续，请联系网站管理员。
_{HTTP ERROR 400}

浏览器地址为https://localhost:7185/Account/Login?returnurl=%2F，调试发现无法匹配控制器中的[HttpPost]方法，提示“未找到资源”。

相关代码 #

AccountController.cs #

// Login
[HttpGet]
public IActionResult Login(string? returnUrl = null)
{
    LoginAccountViewModel loginViewModel = new LoginAccountViewModel();
    loginViewModel.ReturnUrl = returnUrl ?? Url.Content("~/"));
    return View(loginViewModel);
}

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Login(LoginAccountViewModel loginViewModel, string returnUrl)
{
    if (ModelState.IsValid)
    {
        var result = await _signInManager.PasswordSignInAsync(loginViewModel.UserName, loginViewModel.Password, loginViewModel.RememberMe, lockoutOnFailure: false);
        if (result.Succeeded)
        {
            return RedirectToAction("Index", "Home");
        }
        else
        {
            ModelState.AddModelError(string.Empty, "Invalid login attempt.");
            return View(loginViewModel);
        }
    }
    return View(loginViewModel);
}

Login.cshtml #

<form asp-controller="Account" asp-action="Login" asp-route-returnurl="@Model.ReturnUrl" method="post" role="form">
    <div class="p-4 p-md-5 border rounded-3 bg-body-tertiary">
        <!-- Right Side -->
        <div class="col-md-5 col-lg-4 order-md-last">
            <!-- OAuth -->
        </div>
        <!-- Left Side -->
        <div class="col-md-7 col-lg-8">
            <h4 class="mb-3">Account Login Details</h4>
            <form class="needs-validation" novalidate="">
                <div class="row g-3">
                    <!-- UserName -->
                    <div class="col-12">
                        <label asp-for="UserName" class="form-label">Username</label>
                        <div class="input-group has-validation">
                            <span class="input-group-text">@@</span>
                            <input asp-for="UserName" type="text" class="form-control" id="username" placeholder="Username" required>
                            <div class="invalid-feedback">
                                Your username is required.
                            </div>
                        </div>
                    </div>
                    <!-- Password -->
                    <div class="col-12">
                        <label asp-for="Password" class="form-label">Password</label>
                        <input asp-for="Password" type="password" class="form-control" id="password" placeholder="Password">
                        <div class="invalid-feedback">
                            Please enter atleast 6 characters.
                        </div>
                    </div>
                </div>
                <hr class="my-4">
                <!-- Remember Me -->
                <div class="form-check">
                    <label asp-for="RememberMe">
                        <input asp-for="RememberMe" />
                        @Html.DisplayNameFor(m => m.RememberMe)
                    </label>
                </div>
                <hr class="my-4">
                <!-- Login -->
                <div class="form-group mb-3">
                    <button class="w-100 btn btn-primary btn-lg" type="submit">Login</button>
                </div>
                <hr class="my-4">
                <!-- Register -->
                <p>
                    <a class="mb-5" asp-action="Register">Havent Registered yet?</a>
                </p>
            </form>
        </div>
    </div>
</form>

问题原因及解决办法 #

1. 嵌套表单导致提交目标异常 #

Login.cshtml中存在嵌套

<form asp-controller="Account" asp-action="Login" asp-route-returnurl="@Model.ReturnUrl" method="post" role="form" class="needs-validation" novalidate>
    <!-- 保留原有内容，移除内层form标签 -->
</form>

loginViewModel.ReturnUrl = returnUrl ?? Url.Content("~/");

public async Task<IActionResult> Login(LoginAccountViewModel loginViewModel, string? returnUrl = null)

@Html.AntiForgeryToken()