Fatal Error: Uncaught Error: Class 'Redis' not found in /var/www/uc.cl/site/modules/SessionHandlerRedis/SessionHandlerRedis.module:99
Stack trace:
#0 /var/www/uc.cl/site/modules/SessionHandlerRedis/SessionHandlerRedis.module(116): SessionHandlerRedis::_open(NULL)
#1 [internal function]: SessionHandlerRedis->open('/var/lib/php/se...', 'wires')
#2 /var/www/uc.cl/wire/core/Session.php(268): session_start()
#3 /var/www/uc.cl/wire/core/Wire.php(380): ProcessWire\Session->___init()
#4 /var/www/uc.cl/wire/core/WireHooks.php(823): ProcessWire\Wire->_callMethod('___init', Array)
#5 /var/www/uc.cl/wire/core/Wire.php(450): ProcessWire\WireHooks->runHooks(Object(ProcessWire\Session), 'init', Array)
#6 /var/www/uc.cl/wire/core/Session.php(175): ProcessWire\Wire->__call('init', Array)
#7 /var/www/uc.cl/wire/core/ProcessWire.php(514): ProcessWire\Session->__construct(Object(ProcessWire\ProcessWire))
#8 /var/www/uc.cl/wire/core/ProcessWire.php(269): ProcessWire\ProcessWire->lo (line 99 of /var/www/uc.cl/site/modules/SessionHandlerRedis/SessionHandlerRedis.module)

This error message was shown because: site is in debug mode. ($config->debug = true; => /site/config.php). Error has been logged.