我想知道如何修复在将数据表sqoop到oracle中时不断收到的以下错误消息。今天早上我可以换一张table，但之后的每一次尝试都失败了。以下是日志文件中的错误：

Caused by GSSException: No valid credentials provided (Mechanism level: Failed to find any Kerberos tgt)]

我不知道为什么我一直收到这个错误消息，因为没有kerberos票证，我无法登录putty以运行脚本来sqoop表，因此我对a）为什么收到这个错误b）我能做些什么来修复它感到困惑。
如果有人能告诉我哪里出了问题，我将不胜感激。
提前谢谢。
来自日志文件的部分错误消息：

17/01/05 15:08:52 INFO sqoop.Sqoop: Running Sqoop version: 1.4.6-cdh5.7.1
17/01/05 15:08:52 WARN tool.BaseSqoopTool: Setting your password on the command-line is insecure. Consider using -P instead.
17/01/05 15:08:52 INFO oracle.OraOopManagerFactory: Data Connector for Oracle and Hadoop is disabled.
17/01/05 15:08:52 INFO manager.SqlManager: Using default fetchSize of 1000
17/01/05 15:08:52 INFO tool.CodeGenTool: Beginning code generation
17/01/05 15:08:53 INFO manager.OracleManager: Time zone has been set to GMT
17/01/05 15:08:53 INFO manager.SqlManager: Executing SQL statement: SELECT * FROM TABLE_NAME where SNAPSHOT_DATE_TIME >= '01-APR-16' and  (1 = 0) 
17/01/05 15:08:53 INFO manager.SqlManager: Executing SQL statement: SELECT * FROM TABLE_NAME where SNAPSHOT_DATE_TIME >= '01-APR-16' and  (1 = 0) 
17/01/05 15:08:53 INFO orm.CompilationManager: HADOOP_MAPRED_HOME is /opt/cloudera/parcels/CDH/lib/hadoop-mapreduce
Note: /tmp/sqoop-username/compile/ba4df230b0d18377522bbfe053ed3661/QueryResult.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
17/01/05 15:08:55 INFO orm.CompilationManager: Writing jar file: /tmp/sqoop-username/compile/ba4df230b0d18377522bbfe053ed3661/QueryResult.jar
17/01/05 15:08:55 INFO mapreduce.ImportJobBase: Beginning query import.
17/01/05 15:08:55 INFO Configuration.deprecation: mapred.jar is deprecated. Instead, use mapreduce.job.jar
17/01/05 15:08:55 INFO Configuration.deprecation: mapred.map.tasks is deprecated. Instead, use mapreduce.job.maps
17/01/05 15:08:56 WARN security.UserGroupInformation: PriviledgedActionException as:username (auth:KERBEROS) cause:javax.security.sasl.SaslException: GSS initiate failed [Caused by GSSException: No valid credentials provided (Mechanism level: Failed to find any Kerberos tgt)]
17/01/05 15:08:56 WARN ipc.Client: Exception encountered while connecting to the server : javax.security.sasl.SaslException: GSS initiate failed [Caused by GSSException: No valid credentials provided (Mechanism level: Failed to find any Kerberos tgt)]
....