Omeka has encountered an error

Zend_Form_Exception

Method setSubmitButtonText does not exist

#0 /home/azque0/public_html/plugins/GuestUser/controllers/UserController.php(31): Zend_Form->__call('setSubmitButton...', Array)
#1 /home/azque0/public_html/plugins/GuestUser/controllers/UserController.php(31): Omeka_Form_User->setSubmitButtonText('Register')
#2 /home/azque0/public_html/application/libraries/Zend/Controller/Action.php(516): GuestUser_UserController->registerAction()
#3 /home/azque0/public_html/application/libraries/Zend/Controller/Dispatcher/Standard.php(308): Zend_Controller_Action->dispatch('registerAction')
#4 /home/azque0/public_html/application/libraries/Zend/Controller/Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#5 /home/azque0/public_html/application/libraries/Zend/Application/Bootstrap/Bootstrap.php(101): Zend_Controller_Front->dispatch()
#6 /home/azque0/public_html/application/libraries/Zend/Application.php(366): Zend_Application_Bootstrap_Bootstrap->run()
#7 /home/azque0/public_html/application/libraries/Omeka/Application.php(79): Zend_Application->run()
#8 /home/azque0/public_html/index.php(23): Omeka_Application->run()
#9 {main}