The following error is seen when attempting to run an import job against Hive:
Caused by: GSSException: No valid credentials provided (Mechanism level: Failed to find any Kerberos tgt) at sun.security.jgss.krb5.Krb5InitCredential.getInstance(Krb5InitCredential.java:147)
Running the same job using an import job directly against HDFS for the same external table files doesn't produce an error.
There is a bug in Hortonworks Ranger KMS in HDP 2.6.1. Please refer to HADOOP-13155, HADOOP-11628, HADOOP-12787, and HADOOP-12559 per Hortonworks.
Uninstall Hortonworks Ranger KMS or upgrade to the latest maintenance release of HDP to receive Hortonwork's fix.