1.連接數據庫出現警告DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect

解決辦法是：

在連接數據庫時：如下加上

mongoose.connect('mongodb://127.0.0.1:27017/dumall', { useNewUrlParser:true });

2.Failed to lookup view "error" in views

在views文件夾下添加error文件，修改app.js文件

app.set('views', path.join(__dirname,'./views'));//設置引擎，訪問目錄

未修改的是app.set('views', path.join(__dirname,'views'));