Save post as a language and get this error

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1

Whoops\Exception\ErrorException thrown with message “Undefined index: lang”

Stacktrace:
#12 Whoops\Exception\ErrorException in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/user/plugins/ admin/classes/controller.php:1507
#11 Whoops\Run:handleError in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/user/plugins/ admin/classes/controller.php:1507
#10 Grav\Plugin\AdminController:taskSaveas in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/user/plugins/ admin/classes/controller.php:128
#9 call_user_func in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/user/plugins/ admin/classes/controller.php:128
#8 Grav\Plugin\AdminController:execute in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/user/plugins/ admin/admin.php:274
#7 Grav\Plugin\AdminPlugin:initializeController in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/user/plugins/ admin/admin.php:321
#6 Grav\Plugin\AdminPlugin:onPagesInitialized in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/vendor/symfon y/event-dispatcher/EventDispatcher.php:181
#5 cal l_user_func in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/vendor/symfon y/event-dispatcher/EventDispatcher.php:181
#4 Symfony\Component\EventDispatcher\EventDispatcher:doDispatch in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/vendor/symfon y/event-dispatcher/EventDispatcher.php:46
#3 Symfony\Component\EventDispatcher\EventDispatcher:dispatch in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/vendor/rocket theme/toolbox/Event/src/EventDispatcher.php:23
#2 RocketTheme\Toolbox\Event\EventDispatcher:dispatch in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/system/src/Gr av/Common/Grav.php:449
#1 Grav\Common\Grav:fireEvent in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/system/src/Gr av/Common/Grav.php:280
#0 Grav\Common\Grav:process in /home/giaitrit/public_html/nongnghiepsachcongnghecao.com/index.php:38

2

Probably best to create an issue on the Admin Plugin - https://github.com/getgrav/grav-plugin-admin/issues

3

Also please post the content of your user/config/system.yaml file and the path of the page you were editing