Fatal error: Uncaught Error: Call to undefined function proc_open() in /customers/d/8/9/ditishoejewebsiteeruitkanzien.nl/httpd.www/application/libraries/Omeka/File/Derivative/Strategy/ExternalImageMagick.php:204
Stack trace:
#0 /customers/d/8/9/ditishoejewebsiteeruitkanzien.nl/httpd.www/application/libraries/Omeka/File/Derivative/Strategy/ExternalImageMagick.php(186): Omeka_File_Derivative_Strategy_ExternalImageMagick::executeCommand('which convert', NULL, NULL, NULL)
#1 /customers/d/8/9/ditishoejewebsiteeruitkanzien.nl/httpd.www/install/controllers/IndexController.php(58): Omeka_File_Derivative_Strategy_ExternalImageMagick::getDefaultImageMagickDir()
#2 /customers/d/8/9/ditishoejewebsiteeruitkanzien.nl/httpd.www/application/libraries/Zend/Controller/Action.php(516): IndexController->indexAction()
#3 /customers/d/8/9/ditishoejewebsiteeruitkanzien.nl/httpd.www/application/libraries/Zend/Controller/Dispatcher/Standard.php(308): Zend_Controller_Action->dispatch('indexAction')
#4 /customers/d/8/9/ditishoejewebsiteeruitkanzien.nl/httpd.www/application/libraries/Zend/Controller/Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#5 /customers/d/8/9/ditishoejewebsiteeruitkanzien.nl/httpd.www/application/libraries/Zend/Application/Bootstrap/Bootstrap.php(106): Zend_Controller_Front->dispatch()
#6 /customers/d/8/9/ditishoejewebsiteeruitkanzien.nl/httpd.www/application/libraries/Zend/Application.php(384): Zend_Application_Bootstrap_Bootstrap->run()
#7 /customers/d/8/9/ditishoejewebsiteeruitkanzien.nl/httpd.www/install/install.php(48): Zend_Application->run()
#8 {main}
  thrown in /customers/d/8/9/ditishoejewebsiteeruitkanzien.nl/httpd.www/application/libraries/Omeka/File/Derivative/Strategy/ExternalImageMagick.php on line 204