啟動sonarqube 6.7.1 報下面的錯誤：

2018.01.24 10:10:56 WARN  app[][o.e.t.n.Netty4Transport] exception caught on transport layer [[id: 0x146de8cb, L:/127.0.0.1:57099 - R:/127.0.0.1:9001]], closing connection

java.io.IOException: 遠端主機強迫關閉了一個現有的連線。
at sun.nio.ch.SocketDispatcher.read0(Native Method)
at sun.nio.ch.SocketDispatcher.read(Unknown Source)
at sun.nio.ch.IOUtil.readIntoNativeBuffer(Unknown Source)
at sun.nio.ch.IOUtil.read(Unknown Source)
at sun.nio.ch.SocketChannelImpl.read(Unknown Source)
at io.netty.buffer.UnpooledUnsafeDirectByteBuf.setBytes(UnpooledUnsafeDirectByteBuf.java:433)
at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1100)
at io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:372)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:123)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:644)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:579)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:496)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:458)
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)

at java.lang.Thread.run(Unknown Source)

根據sonar.properties裡面的註釋，mysql版本不能低於5.6，

而我裝的mysql版本5.5，升級mysql到5.7版本，問題解決。

另外如果聯接資料庫的帳號密碼錯誤，也會報這個錯。