我正在运行一个node.js服务器，它使用mysql db。我工作的很好，但突然它开始抛出以下错误。
下面是错误的堆栈跟踪：

Error in connecting to DB:  Error: Handshake inactivity timeout
at Handshake.<anonymous> (/home/ubuntu/backend/node_modules/mysql/lib/protocol/Protocol.js:164:17)
at emitNone (events.js:86:13)
at Handshake.emit (events.js:185:7)
at Handshake._onTimeout (/home/ubuntu/backend/node_modules/mysql/lib/protocol/sequences/Sequence.js:129:8)
at ontimeout (timers.js:365:14)
at tryOnTimeout (timers.js:237:5)
at Timer.listOnTimeout (timers.js:207:5)
--------------------
at Protocol._enqueue (/home/ubuntu/backend/node_modules/mysql/lib/protocol/Protocol.js:145:48)
at Protocol.handshake (/home/ubuntu/backend/node_modules/mysql/lib/protocol/Protocol.js:52:23)
at PoolConnection.connect (/home/ubuntu/backend/node_modules/mysql/lib/Connection.js:130:18)
at Pool.getConnection (/home/ubuntu/backend/node_modules/mysql/lib/Pool.js:48:16)
at /home/ubuntu/backend/followcopserver.js:232:11
at Layer.handle [as handle_request] (/home/ubuntu/backend/node_modules/express/lib/router/layer.js:95:5)
at next (/home/ubuntu/backend/node_modules/express/lib/router/route.js:137:13)
at Route.dispatch (/home/ubuntu/backend/node_modules/express/lib/router/route.js:112:3)
at Layer.handle [as handle_request] (/home/ubuntu/backend/node_modules/express/lib/router/layer.js:95:5)
at

非常感谢您的帮助。