Unable to install Prestashop 1.6.1.2

[XAMeLeOH]

Trying to install Prestashop 1.6.1.2 from Plesk application storage I've got an error:

Non-zero exit status returned by script. Output stream: '
PHP Warning: array_merge(): Argument #1 is not an array in /var/www/vhosts/example.com/httpdocs/prestashop/install/controllers/http/process.php on line 266
PHP Fatal error: Uncaught exception 'PrestaShopException' with message 'Property Employee->firstname is not valid' in /var/www/vhosts/example.com/httpdocs/prestashop/classes/ObjectModel.php:909
Stack trace:
#0 /var/www/vhosts/example.com/httpdocs/prestashop/classes/ObjectModel.php(246): ObjectModelCore->validateFields()
#1 /var/www/vhosts/example.com/httpdocs/prestashop/classes/Employee.php(179): ObjectModelCore->getFields()
#2 /var/www/vhosts/example.com/httpdocs/prestashop/classes/ObjectModel.php(652): EmployeeCore->getFields()
#3 /var/www/vhosts/example.com/httpdocs/prestashop/classes/Employee.php(207): ObjectModelCore->update(false)
#4 /var/www/vhosts/example.com/httpdocs/prestashop/classes/ObjectModel.php(445): EmployeeCore->update(false)
#5 /var/www/vhosts/example.com/httpdocs/prestashop/aps_langupdate.php(151): ObjectModelCore->save()
#6 /var/www/configuration/opt/psa/var/apspackages/apscatalogCWT2I0.zipbe70d831-aa4a-f7/cache/scripts/configure(111): include('/var/www/vhosts...')
#7 {main} thrown in /var/www/vhosts/example.com/httpdocs/prestashop/classes/ObjectModel.php on line 909 '.

Please, what can I do to fix this bug or workaround?

I have Parallels Plesk Panel: 11.0.9 , update #63 on Debian 6.0.9. Last update from Dec 21, 2015 07:25 AM.