Unable to change global parameters

Hello,

I made the first installation of ProjeQtOr on my own hosting.
I tried it before on Wamp and everything went fine.

On my hosting, no real problems except an error when I want to set up global parameters.

When I try to save them, I got an error message and in the log file I get that :2021-08-07 18:11:13.154 ***** ERROR ***** [V9.2.2] EXCEPTION *****2021-08-07 18:11:13.154 ***** ERROR ***** [V9.2.2] on file '/var/www/vhosts/sp-ventilation.ch/httpdocs/projeqtor/model/CronExecution.php' at line (63)2021-08-07 18:11:13.155 ***** ERROR ***** [V9.2.2] cause = DateTimeZone::__construct(): Unknown or bad timezone ()2021-08-07 18:11:13.155 ***** ERROR ***** [V9.2.2]    => #0 /var/www/vhosts/sp-ventilation.ch/httpdocs/projeqtor/model/CronExecution.php (63) -> __construct()2021-08-07 18:11:13.155 ***** ERROR ***** [V9.2.2]    => #1 /var/www/vhosts/sp-ventilation.ch/httpdocs/projeqtor/tool/saveParameter.php (311) -> calculNextTime()

Does anybody have an idea to help me ?
I thank you in advance.