Magento 2 what's wrong?

Question

PHP

I've been migrating a plugin from Magento 1 to Magento 2 all day... I've never worked with Magenta before... I got another error:

1 exception(s):
Exception #0 (Magento\Framework\Exception\LocalizedException): Invalid Document 
Element 'accounting': This element is not expected. Expected is one of ( add, update, remove ).
Line: 4


Exception #0 (Magento\Framework\Exception\LocalizedException): Invalid Document 
Element 'accounting': This element is not expected. Expected is one of ( add, update, remove ).
Line: 4

#0 /var/www/html/lib/internal/Magento/Framework/Config/Reader/Filesystem.php(127): Magento\Framework\Config\Reader\Filesystem->_readFiles(Object(Magento\Framework\Config\FileIterator))
#1 /var/www/html/app/code/Magento/Backend/Model/Menu/Config.php(142): Magento\Framework\Config\Reader\Filesystem->read('adminhtml')
#2 /var/www/html/app/code/Magento/Backend/Model/Menu/Config.php(109): Magento\Backend\Model\Menu\Config->_initMenu()
#3 /var/www/html/app/code/Magento/Backend/Model/Url.php(348): Magento\Backend\Model\Menu\Config->getMenu()
#4 /var/www/html/app/code/Magento/Backend/Model/Url.php(308): Magento\Backend\Model\Url->_getMenu()
#5 /var/www/html/app/code/Magento/Backend/App/AbstractAction.php(274): Magento\Backend\Model\Url->getStartupPageUrl()
#6 /var/www/html/app/code/Magento/Backend/App/AbstractAction.php(206): Magento\Backend\App\AbstractAction->_processUrlKeys()
#7 /var/www/html/lib/internal/Magento/Framework/Interception/Interceptor.php(58): Magento\Backend\App\AbstractAction->dispatch(Object(Magento\Framework\App\Request\Http))
#8 /var/www/html/lib/internal/Magento/Framework/Interception/Interceptor.php(138): Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor->___callParent('dispatch', Array)
#9 /var/www/html/app/code/Magento/Backend/App/Action/Plugin/Authentication.php(143): Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor->Magento\Framework\Interception\{closure}(Object(Magento\Framework\App\Request\Http))
#10 /var/www/html/lib/internal/Magento/Framework/Interception/Interceptor.php(135): Magento\Backend\App\Action\Plugin\Authentication->aroundDispatch(Object(Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor), Object(Closure), Object(Magento\Framework\App\Request\Http))
#11 /var/www/html/lib/internal/Magento/Framework/Interception/Interceptor.php(153): Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor->Magento\Framework\Interception\{closure}(Object(Magento\Framework\App\Request\Http))
#12 /var/www/html/var/generation/Magento/Backend/Controller/Adminhtml/Index/Index/Interceptor.php(26): Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor->___callPlugins('dispatch', Array, Array)
#13 /var/www/html/lib/internal/Magento/Framework/App/FrontController.php(55): Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor->dispatch(Object(Magento\Framework\App\Request\Http))
#14 /var/www/html/lib/internal/Magento/Framework/Interception/Interceptor.php(58): Magento\Framework\App\FrontController->dispatch(Object(Magento\Framework\App\Request\Http))
#15 /var/www/html/lib/internal/Magento/Framework/Interception/Interceptor.php(138): Magento\Framework\App\FrontController\Interceptor->___callParent('dispatch', Array)
#16 /var/www/html/lib/internal/Magento/Framework/Interception/Interceptor.php(153): Magento\Framework\App\FrontController\Interceptor->Magento\Framework\Interception\{closure}(Object(Magento\Framework\App\Request\Http))
#17 /var/www/html/var/generation/Magento/Framework/App/FrontController/Interceptor.php(26): Magento\Framework\App\FrontController\Interceptor->___callPlugins('dispatch', Array, Array)
#18 /var/www/html/lib/internal/Magento/Framework/App/Http.php(135): Magento\Framework\App\FrontController\Interceptor->dispatch(Object(Magento\Framework\App\Request\Http))
#19 /var/www/html/lib/internal/Magento/Framework/App/Bootstrap.php(258): Magento\Framework\App\Http->launch()
#20 /var/www/html/index.php(42): Magento\Framework\App\Bootstrap->run(Object(Magento\Framework\App\Http))
#21 {main}

What could be the reason for this and where should I look for the error?
Plugin: https://yadi.sk/d/lgrUHkRPwV84g

Answer 1

#1 /var/www/html/app/code/Magento/Backend/Model/Menu/Config.php(142): Magento\Framework\Config\Reader\Filesystem->read('adminhtml')

This line says that the error is in the config file (xml which) of the extension. Namely, the value of the accounting element does not match the xml description schema.
You might be better off using a special converter to convert extensions from Magento 1 to Magento 2:
https://github.com/magento/code-migration
https://github.com/unirgy/convertm1m2