配置Nginx反向代理.NET Core 6应用HTTPS访问出现404错误求助

已在Nginx上部署MERN栈应用并配置反向代理，运行正常。近期开发了.NET Core 6.0 Web应用，尝试接入Nginx后，通过HTTPS访问域名时页面显示404（域名已配置Certbot SSL证书），但在全新服务器上仅安装.NET和Nginx后，HTTP访问可正常运行。

已配置内容 #

1. .NET应用的systemd服务配置 #

[Unit]
Description=Example .NET Web API App running on Ubuntu

[Service]
WorkingDirectory=/var/www/html/webApp
ExecStart=/usr/bin/dotnet /var/www/html/webApp/web-app.dll
Restart=always
# Restart service after 10 seconds if the dotnet service crashes:
RestartSec=10
KillSignal=SIGINT
SyslogIdentifier=dotnet-example
User=www-data
Environment=ASPNETCORE_ENVIRONMENT=Production
Environment=DOTNET_PRINT_TELEMETRY_MESSAGE=false

[Install]
WantedBy=multi-user.target

2. Nginx配置 #

server {

    #Path to the React front end
    root /var/www/html/MERNAPI/client/build;

    #the main html file
    index index.html;

    #Enter the IP address of your droplet
    server_name mydomain.com www.mydomain.com

     #STORE the nginx access logs for this app here
     access_log /var/log/nginx/mydomain.com.access.log;
     #Store the error logs for this app here
     error_log /var/log/nginx/mydomain.com.error.log;


    client_max_body_size 64M;
    location / {
        # Without this line routing in your Single Page APP will not work  
        try_files $uri $uri/ /index.html =404;
    }

    #REST API BACKEND CONFIG
    location /api {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-NginX-Proxy true;
        proxy_pass http://localhost:3003;
        proxy_ssl_session_reuse off;
        proxy_set_header Host $http_host;
        proxy_cache_bypass $http_upgrade;
        proxy_redirect off;
    }

#Socket IO Config
location /socket.io {
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-NginX-Proxy true;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_http_version 1.1;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $host;
    proxy_pass http://localhost:3003/socket.io/;
}


    location /EV {
         proxy_pass http://127.0.0.1:5000/;
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
         proxy_set_header Connection keep-alive;
         proxy_set_header Host $host;
         proxy_cache_bypass $http_upgrade;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
         proxy_set_header X-Forwarded-Proto $scheme;
        }

    listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/mydomain.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/mydomain.com/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
}

server {
    if ($host = www.mydomain.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot

    if ($host = mydomain.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot

    listen 80;
    listen [::]:80;
    server_name mydomain.com www.mydomain.com;

     #STORE the nginx access logs for this app here
     access_log /var/log/nginx/mydomain.com.access.log;
    return 404; # managed by Certbot
}

3. .NET Program.cs代码 #

using MySqlConnector;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddControllersWithViews();
ConfigurationManager configuration = builder.Configuration;
builder.Services.AddTransient<MySqlConnection>(_ => new MySqlConnection(configuration["ConnectionStrings:Default"]));
builder.Services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
builder.Services.AddSession(options =>
{
    options.IdleTimeout = TimeSpan.FromMinutes(30);//We set Time here 
    options.Cookie.HttpOnly = true;
    options.Cookie.IsEssential = true;
});
builder.Services.AddMvc();
var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Home/Error");
    // The default HSTS value is 30 days. You may want to change this for production scenarios
    app.UseHsts();
    //app.UseHttpsRedirection();
}
app.UseStaticFiles();
app.UseRouting();
app.UseSession();
app.UseAuthorization();

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Account}/{action=Login}/{id?}");

app.Run();

4. appsetting.json配置 #

{
  "ConnectionStrings": {
    "Default": "server=127.0.0.1;port=3306;user=root;password=123;database=xyz"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*"
}

1. 修复Nginx配置语法错误 #

你的Nginx配置存在两处致命语法问题：

• 两处server_name mydomain.com www.mydomain.com末尾都缺少分号，需补全为server_name mydomain.com www.mydomain.com;
• SSL证书行的注释被截断，需修正为完整格式（如# managed by Certbot）

执行命令验证配置语法：

sudo nginx -t

修复后重新加载Nginx：

sudo systemctl reload nginx

2. 确认.NET应用监听端口 #

Nginx将/EV路径代理到127.0.0.1:5000，需确认.NET应用确实在该端口运行：

• 查看应用运行日志：

sudo journalctl -u dotnet-example.service -f

• 检查端口占用情况：

sudo lsof -i :5000

若应用未监听5000端口，可在appsettings.json中添加端口配置：

"Urls": "http://localhost:5000"

或修改systemd服务的环境变量：

Environment=ASPNETCORE_URLS=http://localhost:5000

修改后重启.NET服务：

sudo systemctl restart dotnet-example.service

3. 验证代理路径访问 #

当前Nginx仅将/EV路径代理到.NET应用，需访问https://mydomain.com/EV才能触发.NET应用的路由。若需.NET应用处理其他路径，需调整Nginx的location规则。

4. 检查HTTPS证书配置 #

• 确认SSL证书文件路径正确且Nginx有读取权限：

sudo ls -l /etc/letsencrypt/live/mydomain.com/

• 查看Nginx服务状态，确认HTTPS监听正常：

sudo systemctl status nginx

5. 通过日志定位问题 #

• 查看Nginx错误日志，获取404的具体原因：

sudo tail -f /var/log/nginx/mydomain.com.error.log

• 查看.NET应用日志，确认请求是否到达应用：

sudo journalctl -u dotnet-example.service -f

内容的提问来源于stack exchange，提问作者Dharmeshkumar