MongooseError: OperationXXXbuffering timed out after 10000ms

输出错误信息，发现数据库连接不上

const mongoose  = require('mongoose')
mongoose.connect('mongodb://127.0.0.1:27017/ele-admin') 
.then(() => console.log('数据库连接成功'))
.catch(err => console.log('数据库连接失败', err));

数据库连接失败 
TypeError [ERR_INVALID_URL]: Inva
    at onParseError (internal/url.js:279:9)
    at new URL (internal/url.js:355:5)
    at isAtlas (C:\Users\86176\ele-admin\node_mo\topology\isAtlas.js:17:17)
    at MongooseServerSelectionError.assimilateErmin\node_modules\mongoose\lib\error\serverSelect
    at C:\Users\86176\ele-admin\node_modules\mon3:36 {
  input: '127.0.0.1:27017',
  code: 'ERR_INVALID_URL'
}

将127.0.0.1改成localhost，还是报错

const mongoose  = require('mongoose')
mongoose.connect('mongodb://localhost:27017/ele-admin') 
.then(() => console.log('数据库连接成功'))
.catch(err => console.log('数据库连接失败', err));

MongooseServerSelectionError: Serorts maximum wire version 5, but this version ofes at least 6 (MongoDB 3.6)

数据库连接失败 MongooseServerSelectionError: Serorts maximum wire version 5, but this version ofes at least 6 (MongoDB 3.6)
    at NativeConnection.Connection.openUri (C:\Umodules\mongoose\lib\connection.js:807:32)
    at C:\Users\86176\ele-admin\node_modules\mon
    at C:\Users\86176\ele-admin\node_modules\monrCallback.js:32:5
    at new Promise (<anonymous>)
    at promiseOrCallback (C:\Users\86176\ele-admib\helpers\promiseOrCallback.js:31:10)
n\node_modules\mongoose\lib\index.js:342:20)    
    at Object.<anonymous> (C:\Users\86176\ele-admin\server\index.js:9:10)
    at Module._compile (internal/modules/cjs/loader.js:1085:14)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10) {
  reason: TopologyDescription {
    type: 'Unknown',
    servers: Map(1) { 'localhost:27017' => [ServerDescription] },
    stale: false,
    compatible: true,
    heartbeatFrequencyMS: 10000,
    localThresholdMS: 15,
    logicalSessionTimeoutMinutes: undefined     
  },
  code: undefined
}

应该是mongoose和mongodb版本对不上，可以去这个链接查看对应的版本。
[对应版本查看]（https://mongoosejs.com/docs/compatibility.html#mongodb-server-version-compatibility）

cmd查看mongodb版本：

mongo --version

package.json查看mongoose版本

  "dependencies": {
    "axios": "^0.27.2",
    "core-js": "^3.8.3",
    "cors": "^2.8.5",
    "element-ui": "^2.4.5",
    "express": "^5.0.0-beta.1",
    "mongoose": "^5.2.1",
    "vue": "^2.6.14",
    "vue-router": "^3.5.1"
  },

• 重新安装mongodb：
  网上已经有很多教程了，这里只说一个重新安mongodb会出现的问题，原本的mongodb没能正常停止,如何关闭服务

//客户端登录服务，注意，这里通过localhost登录，如果需要远程登录，必须先登录认证才行。
mongo --port 27017
//#切换到admin库
use admin
//关闭服务
db.shutdownServer()

• 重新安装mongoose:

npm i mongoose@5.2.1 //@指定版本号

mongodb和mongoose版本对应上后就可以正常使用了，具体的使用mongoose对mongodb进行增删改查等操作放在下一篇笔记了。