阿里注册中心 Nacos 启动报错 Unable to start web server

报错内容如下

org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:156)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:544)
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141)
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:744)
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:391)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:312)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1204)
        at com.alibaba.nacos.Nacos.main(Nacos.java:35)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:483)
        at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49)
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:108)
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:58)
        at org.springframework.boot.loader.PropertiesLauncher.main(PropertiesLauncher.java:467)
Caused by: org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
        at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:124)
        at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.<init>(TomcatWebServer.java:86)
        at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:416)
        at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:180)
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:180)
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:153)
        ... 16 common frames omitted
（spring cloud alibaba项目源码 from fhadmin.cn）

因为如果直接在 bin 目录下用鼠标双击 startup.cmd 启动的话，默认的是以 cluster (集群) 的方式启动，直接启动第一个会报 Unable to start embedded Tomcat 错误，改成单机启动：

用记事本打开 bin 目录下查看 startup.cmd

@echo off
rem Copyright 1999-2018 Alibaba Group Holding Ltd.
rem Licensed under the Apache License, Version 2.0 (the "License");
rem you may not use this file except in compliance with the License.
rem You may obtain a copy of the License at
rem
rem      http://www.apache.org/licenses/LICENSE-2.0
rem
rem Unless required by applicable law or agreed to in writing, software
rem distributed under the License is distributed on an "AS IS" BASIS,
rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
rem See the License for the specific language governing permissions and
rem limitations under the License.
if not exist "%JAVA_HOME%\bin\java.exe" echo Please set the JAVA_HOME variable in your environment, We need java(x64)! jdk8 or later is better! & EXIT /B 1
set "JAVA=%JAVA_HOME%\bin\java.exe"
 
setlocal enabledelayedexpansion
 
set BASE_DIR=%~dp0
rem added double quotation marks to avoid the issue caused by the folder names containing spaces.
rem removed the last 5 chars(which means \bin\) to get the base DIR.
set BASE_DIR="%BASE_DIR:~0,-5%"
 
set CUSTOM_SEARCH_LOCATIONS=file:%BASE_DIR%/conf/
 
set MODE="standalone"
set FUNCTION_MODE="all"
set SERVER=nacos-server
set MODE_INDEX=-1
set FUNCTION_MODE_INDEX=-1
set SERVER_INDEX=-1
set EMBEDDED_STORAGE_INDEX=-1
set EMBEDDED_STORAGE=""
 

把 set MODE="cluster" 改为 set MODE="standalone" 即可