JVMCFRE003 bad major version; class=com/microsoft/sqlserver/jdbc/SQLServerDriver, offset=6 on CLM install

I am trying to install CLM 6.0.0 using its tomcat, jre8, and SQL Server (separate platform under MS Server 2012 R2) using JDBC connection. I run the jts/setup, designate SQL Server, and provide password and connection string.  When I try to Test Connection,I keep getting the error

JVMCFRE003 bad major version; class=com/microsoft/sqlserver/jdbc/SQLServerDriver, offset=6

I have set the environment variable SQLSERVER_JDBC_DRIVER_FILE to point to the sqljdbc jar file.  I have tried several different jar files (sqljdbc41.jar, sqljdbc42.jar); each time, I reset the env variable and restarted the server. No luck.  I did not get this error when I originally installed it using the Liberty server using sqljdbc41.jar and jre8.  What is causing this and how can I fix it?