我在一台服务器上部署了 2 个 keymanager 节点、2 个 pub-store 节点、1 个 gateway manager 节点和 2 个 gateway worker 节点，并部署了 nginx 进行负载均衡。当我尝试通过 API 控制台访问 API 时，它报告了以下错误：
TID: [-1234] [] [2016-08-29 21:10:57,237] WARN {org.wso2.carbon.apimgt.gateway.handlers.security.APIAuthenticationHandler} - API authentication failure due to Unclassified Authentication Failure {org.wso2.carbon.apimgt.gateway.handlers.security.APIAuthenticationHandler}
TID: [-1234] [] [2016-08-29 21:10:57,238] ERROR {org.wso2.carbon.apimgt.gateway.handlers.security.APIAuthenticationHandler} - API authentication failed with error 900900 {org.wso2.carbon.apimgt.gateway.handlers.security.APIAuthenticationHandler}
org.wso2.carbon.apimgt.gateway.handlers.security.APISecurityException: Error while accessing backend services for API key validation
at org.wso2.carbon.apimgt.gateway.handlers.security.keys.WSAPIKeyDataStore.getAllURITemplates(WSAPIKeyDataStore.java:77)
at org.wso2.carbon.apimgt.gateway.handlers.security.APIKeyValidator.getAllURITemplates(APIKeyValidator.java:635)
at org.wso2.carbon.apimgt.gateway.handlers.security.APIKeyValidator.doGetAPIInfo(APIKeyValidator.java:487)
at org.wso2.carbon.apimgt.gateway.handlers.security.APIKeyValidator.findMatchingVerb(APIKeyValidator.java:459)
at org.wso2.carbon.apimgt.gateway.handlers.security.APIKeyValidator.getResourceAuthenticationScheme(APIKeyValidator.java:251)
at org.wso2.carbon.apimgt.gateway.handlers.security.oauth.OAuthAuthenticator.authenticate(OAuthAuthenticator.java:119)
at org.wso2.carbon.apimgt.gateway.handlers.security.APIAuthenticationHandler.handleRequest(APIAuthenticationHandler.java:117)
at org.apache.synapse.rest.API.process(API.java:325)
at org.apache.synapse.rest.RESTRequestHandler.dispatchToAPI(RESTRequestHandler.java:90)
at org.apache.synapse.rest.RESTRequestHandler.process(RESTRequestHandler.java:69)
at org.apache.synapse.core.axis2.Axis2SynapseEnvironment.injectMessage(Axis2SynapseEnvironment.java:300)
at org.apache.synapse.core.axis2.SynapseMessageReceiver.receive(SynapseMessageReceiver.java:75)
at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:180)
at org.apache.synapse.transport.passthru.ServerWorker.processNonEntityEnclosingRESTHandler(ServerWorker.java:319)
at org.apache.synapse.transport.passthru.ServerWorker.run(ServerWorker.java:152)
at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:172)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.wso2.carbon.apimgt.gateway.handlers.security.APISecurityException: Error while accessing backend services for API key validation
at org.wso2.carbon.apimgt.gateway.handlers.security.keys.APIKeyValidatorClient.getAllURITemplates(APIKeyValidatorClient.java:171)
at org.wso2.carbon.apimgt.gateway.handlers.security.keys.WSAPIKeyDataStore.getAllURITemplates(WSAPIKeyDataStore.java:75)
... 18 more
Caused by: java.lang.NullPointerException
at org.wso2.carbon.apimgt.gateway.handlers.security.keys.APIKeyValidatorClient.toTemplates(APIKeyValidatorClient.java:193)
at org.wso2.carbon.apimgt.gateway.handlers.security.keys.APIKeyValidatorClient.getAllURITemplates(APIKeyValidatorClient.java:166)
... 19 more
什么配置问题？