ASP.NET Core Web API的默认错误页面来自于提供程序。可以通过更改提供程序来自定义错误页面。

1. 创建自定义错误页面视图文件。在Views/Shared文件夹下创建一个名为“Error.cshtml”的视图文件。在该文件中可以使用HTML、CSS和JavaScript来自定义错误页面的外观和行为。

2. 创建自定义错误处理程序。在Startup.cs文件中添加以下代码：

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    if (env.IsDevelopment())
    {
        // 省略其他中间件
        app.UseDeveloperExceptionPage();
    }
    else
    {
        // 省略其他中间件
        app.UseExceptionHandler("/Error");
    }
}

public static void UseExceptionHandler(this IApplicationBuilder app, string path)
{
    app.UseExceptionHandler(new ExceptionHandlerOptions
    {
        ExceptionHandler = new ErrorHandlingMiddleware(path).Invoke
    });
}

3. 创建自定义异常处理中间件。在中间件文件夹下创建一个名为“ErrorHandlingMiddleware.cs”的文件，并添加以下代码：

public class ErrorHandlingMiddleware
{
    private readonly RequestDelegate next;
    private readonly string errorPath;

    public ErrorHandlingMiddleware(RequestDelegate next, string errorPath)
    {
        this.next = next;
        this.errorPath = errorPath;
    }

    public async Task Invoke(HttpContext context)
    {
        try
        {
            await next(context);
        }
        catch (Exception ex)
        {
            LogException(ex); // 可以在这里记录异常日志

            context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
            context.Response.ContentType = "text/html";

            await context.Response.WriteAsync(GetErrorHtml());
        }
    }

    private string GetErrorHtml()
    {
        return new ViewRenderer().RenderViewToString(
            errorPath,
            new ErrorViewModel { Message = "An error occurred while processing your request." });
    }

    private static void LogException(Exception ex)
    {
        // 在此处记录异常日志
    }
}

public class ViewRenderer : IViewRenderer
{
    private readonly IRazorViewEngine razorViewEngine;
    private readonly ITempDataProvider tempDataProvider;
    private readonly IServiceProvider serviceProvider;

    public ViewRenderer(
        IRazorViewEngine razorViewEngine,
        ITempDataProvider tempDataProvider,
        IServiceProvider serviceProvider)
    {
        this.razorViewEngine = razorViewEngine;
        this.tempDataProvider = tempDataProvider;
        this.serviceProvider = serviceProvider;
    }

    public ViewRenderer() : this(
        new RazorViewEngine(
            new EmptyModelMetadataProvider(),
            new RazorViewLocator(),
            new DefaultViewPageActivator(),
            Enumerable.Empty(),
            new OptionsAccessor()),
        new SessionStateTempDataProvider(),
        new ServiceProvider())
    { }

    public string RenderViewToString(string viewName, object model)
    {
        var httpContext = new DefaultHttpContext { RequestServices = serviceProvider };
        var actionContext = new ActionContext(
            httpContext,
            new RouteData(),
            new ActionDescriptor());

        var viewResult = razorViewEngine.Find