这是什么错误？怎样修复？ Could not load com.mysql.jdbc.SQLError.

信息: Illegal access: this web application instance has been stopped already. Could not load com.mysql.jdbc.SQLError. The eventual following stack trace is caused by an error thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access, and has no functional impact.
java.lang.IllegalStateException
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1587)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1546)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3270)
at com.mysql.jdbc.MysqlIO.quit(MysqlIO.java:1659)
at com.mysql.jdbc.ConnectionImpl.realClose(ConnectionImpl.java:4296)
at com.mysql.jdbc.ConnectionImpl.cleanup(ConnectionImpl.java:1265)
at com.mysql.jdbc.ConnectionImpl.finalize(ConnectionImpl.java:2667)
at java.lang.System$2.invokeFinalize(System.java:1213)
at java.lang.ref.Finalizer.runFinalizer(Finalizer.java:98)
at java.lang.ref.Finalizer.access$100(Finalizer.java:34)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:210)
非常感谢！

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