org.netbeans.api.db.explorer.DatabaseException: Communications link failure

Last packet sent to the server was 39 ms ago.
        at org.netbeans.modules.db.explorer.infos.TableNodeInfo.initChildren(TableNodeInfo.java:167)
        at org.netbeans.modules.db.explorer.infos.TableNodeInfo.initChildren(TableNodeInfo.java:78)
        at org.netbeans.modules.db.explorer.infos.DatabaseNodeInfo.loadChildren(DatabaseNodeInfo.java:710)
        at org.netbeans.modules.db.explorer.infos.DatabaseNodeInfo.getChildren(DatabaseNodeInfo.java:698)
        at org.netbeans.modules.db.explorer.nodes.DatabaseNode$DatabaseNodeChildFactory.createKeys(DatabaseNode.java:382)
        at org.openide.nodes.AsynchChildren.run(AsynchChildren.java:147)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:572)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:997)
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Last packet sent to the server was 39 ms ago.
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(NativeConstructorAccessorImpl.java:0)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
        at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
        at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2985)
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2871)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3414)
        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1936)
        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2060)
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2536)
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2465)
        at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1383)
        at com.mysql.jdbc.DatabaseMetaData$7.forEach(DatabaseMetaData.java:3915)
        at com.mysql.jdbc.IterateBlock.doForAll(IterateBlock.java:50)
        at com.mysql.jdbc.DatabaseMetaData.getPrimaryKeys(DatabaseMetaData.java:3899)
        at org.netbeans.lib.ddl.adaptors.DefaultAdaptor.getPrimaryKeys(DefaultAdaptor.java:3558)
        at org.netbeans.lib.ddl.impl.DriverSpecification.getPrimaryKeys(DriverSpecification.java:157)
        at org.netbeans.modules.db.explorer.infos.TableNodeInfo.initChildren(TableNodeInfo.java:88)
        at org.netbeans.modules.db.explorer.infos.TableNodeInfo.initChildren(TableNodeInfo.java:78)
        at org.netbeans.modules.db.explorer.infos.DatabaseNodeInfo.loadChildren(DatabaseNodeInfo.java:710)
        at org.netbeans.modules.db.explorer.infos.DatabaseNodeInfo.getChildren(DatabaseNodeInfo.java:698)
        at org.netbeans.modules.db.explorer.nodes.DatabaseNode$DatabaseNodeChildFactory.createKeys(DatabaseNode.java:382)
        at org.openide.nodes.AsynchChildren.run(AsynchChildren.java:147)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:572)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:997)
java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
        at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2431)
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2882)
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2871)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3414)
        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1936)
        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2060)
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2536)
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2465)
        at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1383)
        at com.mysql.jdbc.DatabaseMetaData$7.forEach(DatabaseMetaData.java:3915)
        at com.mysql.jdbc.IterateBlock.doForAll(IterateBlock.java:50)
        at com.mysql.jdbc.DatabaseMetaData.getPrimaryKeys(DatabaseMetaData.java:3899)
        at org.netbeans.lib.ddl.adaptors.DefaultAdaptor.getPrimaryKeys(DefaultAdaptor.java:3558)
        at org.netbeans.lib.ddl.impl.DriverSpecification.getPrimaryKeys(DriverSpecification.java:157)
        at org.netbeans.modules.db.explorer.infos.TableNodeInfo.initChildren(TableNodeInfo.java:88)
        at org.netbeans.modules.db.explorer.infos.TableNodeInfo.initChildren(TableNodeInfo.java:78)
        at org.netbeans.modules.db.explorer.infos.DatabaseNodeInfo.loadChildren(DatabaseNodeInfo.java:710)
        at org.netbeans.modules.db.explorer.infos.DatabaseNodeInfo.getChildren(DatabaseNodeInfo.java:698)
        at org.netbeans.modules.db.explorer.nodes.DatabaseNode$DatabaseNodeChildFactory.createKeys(DatabaseNode.java:382)
        at org.openide.nodes.AsynchChildren.run(AsynchChildren.java:147)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:572)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:997)