Что за ошибка Redis — 'RedisException' with message 'protocol error, got 'E' ?

PHP Fatal error: Uncaught exception 'RedisException' with message 'protocol error, got 'E' as reply type byte

' in /var/www/ftp.modul/data/www/domain/application/models/autoincrement_model.php:77
Stack trace:
#0 /var/www/ftp.modul/data/www/site/application/models/autoincrement_model.php(77): Redis->get('autoincrement:o...')
#1 /var/www/ftp.modul/data/www/domain/application/models/autoincrement_model.php(63): Autoincrement_model->fill_autoincrements(Array)
#2 /var/www/ftp.modul/data/www/domain/application/controllers/scripts.php(52): Autoincrement_model->check_autoincrements()
#3 [internal function]: Scripts->check_redis()
#4 /var/www/ftp.modul/data/www/domain/system/core/CodeIgniter.php(359): call_user_func_array(Array, Array)
#5 /var/www/ftp.modul/data/www/domain/index.php(206): require_once('/var/www/ftp.mo...')
#6 {main}

Используется:
CodeIgniter 2.2
PHP 5.3.x
MySQL 5.1.x
Redis 2.4.15