upgrade 5.5 to 5.6 will not startup ERROR Aborting last message in error.log WHY?

Why can I not startup up 5.6.29 on a CentOS 7 host
where Percona 5.5.28 runs w/o problem

Stop slave and shutdown 5.5.28 clean
removed old symlink to mysql 5.5.28 binaries.

NEXT yum install Percona-Server-shared-56-5.6.29-rel76.2.el6.x86_64.rpm
yum install Percona-Server-client-56-5.6.29-rel76.2.el6.x86_64.rpm
yum install Percona-Server-server-56-5.6.29-rel76.2.el6.x86_64.rpm

Want to startup Mysql first time and run mysql_upgrade script

/usr/sbin/mysqld --skip-grant-tables --user=mysql & [1] 2051 ]# 2016-03-25 11:33:59 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details). 2016-03-25 11:33:59 0 [Note] /usr/sbin/mysqld (mysqld 5.6.29-76.2-log) starting as process 2051 … 2016-03-25 11:33:59 2051 [ERROR] Can’t read from messagefile ‘/usr/share/mysql/english/errmsg.sys’ BUT it never starts up and there is not real info in the error.log only show ERROR Aborting … why not?

2016-03-25 11:12:30 1825 [Note] InnoDB: Waiting for purge to start
2016-03-25 11:12:30 1825 [Note] InnoDB: Percona XtraDB (http://www.percona.com) 5.6.29-76.2 started; log sequence number 23270845141317
2016-03-25 11:12:30 1825 [ERROR] /usr/sbin/mysqld: unknown variable ‘table_cache=4096’
2016-03-25 11:12:30 1825 [ERROR] Aborting

2016-03-25 11:12:30 1825 [Note] Binlog end
2016-03-25 11:12:30 1825 [Note] Shutting down

2016-03-25 11:12:30 1825 [ERROR] /usr/sbin/mysqld: unknown variable 'table_cache=4096
Renamed the table_cache system variable to table_open_cache. Any scripts that refer to table_cache should be updated to use the new name. So, replace table_cache with table_open_cache in my.cnf and restart mysql server. It should fix the problem. I found this too https://bugs.mysql.com/bug.php?id=68315

MySQL was complaining on this 55 variables when trying to start 56 percona server
So I comment them out - hence it should default to table_open_cache
grep ‘##YE##’ /etc/my.cnf
##YE##character_set_client = utf8
##YE##basedir = /usr/local/mysql
##YE##table_cache = 4096
##YE##innodb_additional_mem_pool_size = 256M

was to change basedir from (55) basedir=/usr/local/mysql (Tar ball install and symlink install to /usr/local/mysql)
to (56) basedir=/usr (rpm install of Percona server)
then Mysql 5.6 server started up w/o problem
and I could proceed with mysql_upgrade script etc
MySQL 56 slave is currently up running and attached to a 55 Master …

mysql> select @@table_open_cache;
| @@table_open_cache |
| 2000 |