我有一个 GWT/GXT 应用程序，它通过“gwt:run”（托管模式）运行良好，但在 Tomcat 服务器上它崩溃了JdbcSQLException，我不明白，因为导致异常的调用是服务器代码不是反正翻译成javascript。此外，我自己没有编写导致异常的代码，它包含在我的应用程序使用的库中。
有人能告诉我如何解决这个错误吗？
PS：这里根据请求抛出异常的代码语句：
private Connection conn;
[...]
conn = DriverManager.getConnection("jdbc:h2:"+databaseDirectory+"/"+databaseName+jdbcString, "sa", "");
[...]
PreparedStatement ps=conn.prepareStatement("SELECT * FROM QUERY_CACHE WHERE QUERYHASH=? LIMIT 1"); // throws the exception
完整的堆栈跟踪：
org.h2.jdbc.JdbcSQLException: Connection is broken: "unexpected status 7274613" [90067-143]
at org.h2.message.DbException.getJdbcSQLException(DbException.java:327)
at org.h2.message.DbException.get(DbException.java:167)
at org.h2.message.DbException.get(DbException.java:144)
at org.h2.engine.SessionRemote.done(SessionRemote.java:558)
at org.h2.command.CommandRemote.prepare(CommandRemote.java:68)
at org.h2.command.CommandRemote.<init>(CommandRemote.java:47)
at org.h2.engine.SessionRemote.prepareCommand(SessionRemote.java:421)
at org.h2.jdbc.JdbcConnection.prepareCommand(JdbcConnection.java:1052)
at org.h2.jdbc.JdbcPreparedStatement.<init>(JdbcPreparedStatement.java:71)
at org.h2.jdbc.JdbcConnection.prepareStatement(JdbcConnection.java:233)
at org.dllearner.kb.sparql.ExtractionDBCache.executeSelectQuery(ExtractionDBCache.java:183)
at org.dllearner.kb.sparql.ExtractionDBCache.executeSelectQuery(ExtractionDBCache.java:174)
at org.dllearner.reasoning.SPARQLReasoner.executeSelectQuery(SPARQLReasoner.java:887)
at org.dllearner.reasoning.SPARQLReasoner.getSubClasses(SPARQLReasoner.java:766)
at org.dllearner.reasoning.SPARQLReasoner.getSubClasses(SPARQLReasoner.java:745)
at org.dllearner.reasoning.SPARQLReasoner.prepareSubsumptionHierarchy(SPARQLReasoner.java:124)
at org.dllearner.algorithm.tbsl.learning.SPARQLTemplateBasedLearner.setEndpoint(SPARQLTemplateBasedLearner.java:229)
at org.autosparql.server.search.TBSLSearch.getExamples(TBSLSearch.java:117)
at org.autosparql.server.search.TBSLSearch.getExamples(TBSLSearch.java:105)
at org.autosparql.server.AutoSPARQLSession.getExamples(AutoSPARQLSession.java:354)
at org.autosparql.server.AutoSPARQLServiceImpl.getExamples(AutoSPARQLServiceImpl.java:86)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:569)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:208)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:679)
java.lang.NullPointerException
at org.dllearner.kb.sparql.SparqlQuery.convertJSONtoResultSet(SparqlQuery.java:297)
at org.dllearner.reasoning.SPARQLReasoner.executeSelectQuery(SPARQLReasoner.java:887)
at org.dllearner.reasoning.SPARQLReasoner.getSubClasses(SPARQLReasoner.java:766)
at org.dllearner.reasoning.SPARQLReasoner.getSubClasses(SPARQLReasoner.java:745)
at org.dllearner.reasoning.SPARQLReasoner.prepareSubsumptionHierarchy(SPARQLReasoner.java:124)
at org.dllearner.algorithm.tbsl.learning.SPARQLTemplateBasedLearner.setEndpoint(SPARQLTemplateBasedLearner.java:229)
at org.autosparql.server.search.TBSLSearch.getExamples(TBSLSearch.java:117)
at org.autosparql.server.search.TBSLSearch.getExamples(TBSLSearch.java:105)
at org.autosparql.server.AutoSPARQLSession.getExamples(AutoSPARQLSession.java:354)
at org.autosparql.server.AutoSPARQLServiceImpl.getExamples(AutoSPARQLServiceImpl.java:86)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:569)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:208)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:679)