500 : サーバ内部でエラーが発生しました。

Question

ログイン画面にアクセスすると500エラーと表示され、ログには以下のようなエラーが出力される。
以下のサイトを参考し、解決出来なかった。
https://www.tachi-machi.net/entry/2018/04/18/131017

[ERROR] e.http-500 - [] java.lang.NoClassDefFoundError: Could not initialize class jp.co.intra_mart.foundation.router.RouterFactory$LazyHolder
javax.servlet.ServletException: java.lang.NoClassDefFoundError: Could not initialize class jp.co.intra_mart.foundation.router.RouterFactory$LazyHolder
	at com.caucho.server.dispatch.FilterManager.createFilter(FilterManager.java:234)
	at com.caucho.server.dispatch.FilterMapper.buildDispatchChain(FilterMapper.java:169)
	at com.caucho.server.webapp.WebApp.buildInvocation(WebApp.java:4215)
	at com.caucho.server.webapp.WebAppContainer.buildInvocation(WebAppContainer.java:798)
	at com.caucho.server.host.Host.buildInvocation(Host.java:753)
	at com.caucho.server.host.HostContainer.buildInvocation(HostContainer.java:320)
	at com.caucho.server.cluster.ServletService.buildInvocation(ServletService.java:1068)
	at com.caucho.server.dispatch.InvocationServer.buildInvocation(InvocationServer.java:250)
	at com.caucho.server.dispatch.InvocationServer.buildInvocation(InvocationServer.java:223)
	at com.caucho.server.http.AbstractHttpRequest.buildInvocation(AbstractHttpRequest.java:1610)
	at com.caucho.server.http.AbstractHttpRequest.getInvocation(AbstractHttpRequest.java:1583)
	at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:825)
	at com.caucho.network.listen.TcpSocketLink.dispatchRequest(TcpSocketLink.java:1395)
	at com.caucho.network.listen.TcpSocketLink.handleRequest(TcpSocketLink.java:1351)
	at com.caucho.network.listen.TcpSocketLink.handleRequestsImpl(TcpSocketLink.java:1335)
	at com.caucho.network.listen.TcpSocketLink.handleRequests(TcpSocketLink.java:1243)
	at com.caucho.network.listen.TcpSocketLink.handleAcceptTaskImpl(TcpSocketLink.java:1037)
	at com.caucho.network.listen.ConnectionTask.runThread(ConnectionTask.java:117)
	at com.caucho.network.listen.ConnectionTask.run(ConnectionTask.java:93)
	at com.caucho.network.listen.SocketLinkThreadLauncher.handleTasks(SocketLinkThreadLauncher.java:175)
	at com.caucho.network.listen.TcpSocketAcceptThread.run(TcpSocketAcceptThread.java:61)
	at com.caucho.env.thread2.ResinThread2.runTasks(ResinThread2.java:173)
	at com.caucho.env.thread2.ResinThread2.run(ResinThread2.java:118)