当我在测试 GCM 时尝试访问我注册的设备本地开发应用服务器时出现以下错误。有人可以帮忙吗。我按照这里的步骤https://developers.google.com/eclipse/docs/endpoints-androidconnected-gae 我可以在 //:localhost:8888/_ah/admin 中看到注册的设备。但是当我打开 //:localhost:8888/ 我看到下面的错误。页面加载，但注册的设备未显示，我在发送按钮下方看到此错误消息。
There was a problem contacting the server when attempting to list the registered devices.
Please refresh the page and try again in a short while. Here's the error information:
<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"/>
<title>Error 500 INTERNAL_SERVER_ERROR</title> </head> <body><h2>HTTP ERROR 500</h2> <p>Problem
accessing /_ah/api/rpc. Reason: <pre> INTERNAL_SERVER_ERROR</pre></p><h3>Caused
by:</h3><pre>java.lang.NullPointerException at
com.google.api.server.spi.tools.devserver.ApiServlet.addDefaultParams(ApiServlet.java:264) at
com.google.api.server.spi.tools.devserver.ApiServlet.addParametersToMap(ApiServlet.java:257) at
com.google.api.server.spi.tools.devserver.ApiServlet.doSingleBackendCall(ApiServlet.java:239)
at com.google.api.server.spi.tools.devserver.RpcApiServlet.doSingleBackendCall
(RpcApiServlet.java:131) at com.google.api.server.spi.tools.devserver.RpcApiServlet.service
(RpcApiServlet.java:112) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at
org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166) at
com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74) at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at
com.google.appengine.tools.development.ResponseRewriterFilter.doFilter
(ResponseRewriterFilter.java:123) at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at
com.google.appengine.tools.development.HeaderVerificationFilter.doFilter
(HeaderVerificationFilter.java:34) at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at
com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:63) at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at
com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter
(TransactionCleanupFilter.java:43) at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at
com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125) at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at
com.google.appengine.tools.development.DevAppServerServersFilter.doDirectRequest
(DevAppServerServersFilter.java:369) at
com.google.appengine.tools.development.DevAppServerServersFilter.doDirectServerRequest
(DevAppServerServersFilter.java:352) at
com.google.appengine.tools.development.DevAppServerServersFilter.doFilter
(DevAppServerServersFilter.java:115) at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at
org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388) at
org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) at
org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) at
org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) at
org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) at
com.google.appengine.tools.development.DevAppEngineWebAppContext.handle
(DevAppEngineWebAppContext.java:97) at org.mortbay.jetty.handler.HandlerWrapper.handle
(HandlerWrapper.java:152) at
com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle
(JettyContainerService.java:438) at org.mortbay.jetty.handler.HandlerWrapper.handle
(HandlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:326) at
org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) at
org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938) at
org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755) at
org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218) at
org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) at
org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409) at
org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582) </pre>
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