Safemode error and app problem after update (no replies)

When i updated Piwik to te latest version right after ik cannot see most modules and the error given is this:

Oops… there was a problem during the request. Maybe the server had a temporary issue, or maybe you requested a report with too much data. Please try again. If this error occurs repeatedly please contact your Piwik administrator for assistance.

So using the piwik software is now impossible.

Also i get the following error sins latest update:

There is an error. Please report the message (Piwik 2.5.0-b2) and full backtrace in the Piwik forums (please do a Search first as it might have been reported already!).

Warning: shell_exec(): Cannot execute using backquotes in Safe Mode in /home/admin/domains/hetespellen.be/public_html/piwik/core/CliMulti/Process.php on line 170

Backtrace -->

#0 Piwik\Error::errorHandler(...) called at [:]
#1 shell_exec(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/CliMulti/Process.php:170]
#2 Piwik\CliMulti\Process::isSystemNotSupported(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/CliMulti/Process.php:153]
#3 Piwik\CliMulti\Process::isSupported(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/CliMulti.php:163]
#4 Piwik\CliMulti->supportsAsync(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/CliMulti.php:46]
#5 Piwik\CliMulti->__construct(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/plugins/Installation/SystemCheck.php:187]
#6 Piwik\Plugins\Installation\SystemCheck::getSystemInformation(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/plugins/Installation/Controller.php:406]
#7 Piwik\Plugins\Installation\Controller::getSystemInformation(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/plugins/Installation/Controller.php:604]
#8 Piwik\Plugins\Installation\Controller->setupSystemCheckView(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/plugins/Installation/Controller.php:429]
#9 Piwik\Plugins\Installation\Controller->systemCheckPage(...) called at [:]
#10 call_user_func_array(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/FrontController.php:576]
#11 Piwik\FrontController->doDispatch(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/FrontController.php:86]
#12 Piwik\FrontController->dispatch(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/dispatch.php:34]
#13 require_once(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/index.php:47]

And next error

There is an error. Please report the message (Piwik 2.5.0-b2) and full backtrace in the Piwik forums (please do a Search first as it might have been reported already!).

Warning: shell_exec(): Cannot execute using backquotes in Safe Mode in /home/admin/domains/hetespellen.be/public_html/piwik/core/CliMulti/Process.php on line 170

Backtrace -->

#0 Piwik\Error::errorHandler(...) called at [:]
#1 shell_exec(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/CliMulti/Process.php:170]
#2 Piwik\CliMulti\Process::isSystemNotSupported(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/CliMulti/Process.php:153]
#3 Piwik\CliMulti\Process::isSupported(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/CliMulti.php:163]
#4 Piwik\CliMulti->supportsAsync(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/plugins/Installation/SystemCheck.php:188]
#5 Piwik\Plugins\Installation\SystemCheck::getSystemInformation(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/plugins/Installation/Controller.php:406]
#6 Piwik\Plugins\Installation\Controller::getSystemInformation(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/plugins/Installation/Controller.php:604]
#7 Piwik\Plugins\Installation\Controller->setupSystemCheckView(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/plugins/Installation/Controller.php:429]
#8 Piwik\Plugins\Installation\Controller->systemCheckPage(...) called at [:]
#9 call_user_func_array(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/FrontController.php:576]
#10 Piwik\FrontController->doDispatch(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/FrontController.php:86]
#11 Piwik\FrontController->dispatch(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/core/dispatch.php:34]
#12 require_once(...) called at [/home/admin/domains/hetespellen.be/public_html/piwik/index.php:47]