Error after upgrading from beta1 to beta2

In manual mode - standard folders system public app writable.
Here is the full log:
CRITICAL - 2019-04-06 07:33:20 --> preg_match() expects parameter 2 to be string, array given
#0 [internal function]: CodeIgniter\Debug\Exceptions->errorHandler(2, 'preg_match() ex...', '/home/ysu.su/h/...', 144, Array)
#1 /home/ysu.su/h/system/Debug/Toolbar.php(144): preg_match('~[^\\x20-\\x7E\\t\\...', Array)
#2 /home/ysu.su/h/system/Debug/Toolbar.php(331): CodeIgniter\Debug\Toolbar->run(1554525200.6966, 0.0864, Object(CodeIgniter\HTTP\IncomingRequest), Object(CodeIgniter\HTTP\Response))
#3 /home/ysu.su/h/system/Filters/DebugToolbar.php(74): CodeIgniter\Debug\Toolbar->prepare()
#4 /home/ysu.su/h/system/Filters/Filters.php(176): CodeIgniter\Filters\DebugToolbar->after(Object(CodeIgniter\HTTP\IncomingRequest), Object(CodeIgniter\HTTP\Response))
#5 /home/ysu.su/h/system/CodeIgniter.php(346): CodeIgniter\Filters\Filters->run('/', 'after')
#6 /home/ysu.su/h/system/CodeIgniter.php(238): CodeIgniter\CodeIgniter->handleRequest(NULL, Object(Config\Cache), false)
#7 /home/ysu.su/h/public/index.php(37): CodeIgniter\CodeIgniter->run()
#8 {main}