There has been an error processing your request Exception printing is disabled by default for securi

[Hankaizhane1bd]

Anyone know what happens ? My magento is 2.3.4  , this is happened after i installed a theme, the website is normal .but when i only open /admin/  it shows this 

There has been an error processing your request Exception printing is disabled by default for secure......

and here is the error code 

1 exception(s):
Exception #0 (OutOfRangeException): Specified invalid parent id (Magento_Backend::mgs)

Exception #0 (OutOfRangeException): Specified invalid parent id (Magento_Backend::mgs)
<pre>#1 Magento\Backend\Model\Menu\Builder\Interceptor->___callParent('getResult', array(&Magento\Backend\Model\Menu#00000000055f6116000000004505f984#)) called at [vendor/magento/framework/Interception/Interceptor.php:138]
#2 Magento\Backend\Model\Menu\Builder\Interceptor->Magento\Framework\Interception\{closure}(&Magento\Backend\Model\Menu#00000000055f6116000000004505f984#) called at [vendor/magento/framework/Interception/Interceptor.php:153]
#3 Magento\Backend\Model\Menu\Builder\Interceptor->___callPlugins('getResult', array(&Magento\Backend\Model\Menu#00000000055f6116000000004505f984#), array(array('SetupMenuBuilder'))) called at [generated/code/Magento/Backend/Model/Menu/Builder/Interceptor.php:39]
#4 Magento\Backend\Model\Menu\Builder\Interceptor->getResult(&Magento\Backend\Model\Menu#00000000055f6116000000004505f984#) called at [vendor/magento/module-backend/Model/Menu/Config.php:148]
#5 Magento\Backend\Model\Menu\Config->_initMenu() called at [vendor/magento/module-backend/Model/Menu/Config.php:111]
#6 Magento\Backend\Model\Menu\Config->getMenu() called at [vendor/magento/module-backend/Model/Url.php:365]
#7 Magento\Backend\Model\Url->_getMenu() called at [vendor/magento/module-backend/Model/Url.php:325]
#8 Magento\Backend\Model\Url->getStartupPageUrl() called at [vendor/magento/module-backend/App/AbstractAction.php:281]
#9 Magento\Backend\App\AbstractAction->_processUrlKeys() called at [generated/code/Magento/Backend/Controller/Adminhtml/Index/Index/Interceptor.php:50]
#10 Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor->_processUrlKeys() called at [vendor/magento/module-backend/App/Request/BackendValidator.php:175]
#11 Magento\Backend\App\Request\BackendValidator->validate(&Magento\Framework\App\Request\Http#00000000055f6570000000004505f984#, &Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor#00000000055f6297000000004505f984#) called at [vendor/magento/framework/App/Request/CompositeValidator.php:40]
#12 Magento\Framework\App\Request\CompositeValidator->validate(&Magento\Framework\App\Request\Http#00000000055f6570000000004505f984#, &Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor#00000000055f6297000000004505f984#) called at [vendor/magento/framework/App/FrontController.php:137]
#13 Magento\Framework\App\FrontController->processRequest(&Magento\Framework\App\Request\Http#00000000055f6570000000004505f984#, &Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor#00000000055f6297000000004505f984#) called at [vendor/magento/framework/App/FrontController.php:98]
#14 Magento\Framework\App\FrontController->dispatch(&Magento\Framework\App\Request\Http#00000000055f6570000000004505f984#) called at [vendor/magento/framework/Interception/Interceptor.php:58]
#15 Magento\Framework\App\FrontController\Interceptor->___callParent('dispatch', array(&Magento\Framework\App\Request\Http#00000000055f6570000000004505f984#)) called at [vendor/magento/framework/Interception/Interceptor.php:138]
#16 Magento\Framework\App\FrontController\Interceptor->Magento\Framework\Interception\{closure}(&Magento\Framework\App\Request\Http#00000000055f6570000000004505f984#) called at [vendor/magento/framework/Interception/Interceptor.php:153]
#17 Magento\Framework\App\FrontController\Interceptor->___callPlugins('dispatch', array(&Magento\Framework\App\Request\Http#00000000055f6570000000004505f984#), array(array('default_store_se...', 'page_cache_from_...', 'storeCookieValid...', 'install', 'configHash'))) called at [generated/code/Magento/Framework/App/FrontController/Interceptor.php:26]
#18 Magento\Framework\App\FrontController\Interceptor->dispatch(&Magento\Framework\App\Request\Http#00000000055f6570000000004505f984#) called at [vendor/magento/framework/App/Http.php:116]
#19 Magento\Framework\App\Http->launch() called at [generated/code/Magento/Framework/App/Http/Interceptor.php:24]
#20 Magento\Framework\App\Http\Interceptor->launch() called at [vendor/magento/framework/App/Bootstrap.php:261]
#21 Magento\Framework\App\Bootstrap->run(&Magento\Framework\App\Http\Interceptor#00000000055f6440000000004505f984#) called at [index.php:39]
</pre>

any one know where is problem .and how to fix it ? highly appreciate 

[smita_kagwade]

Hello @Hankaizhane1bd ,

Solution1:

Maybe one of the menu.xml  from your new module is written incorrectly, check if is there any wrong parent id for menus given 

There is no parent id name with mgs so it will throw an error

See below sample code is for page menu

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Backend:etc/menu.xsd">
    <menu>
        <add id="Magento_Cms::cms_page" title="Pages" module="Magento_Cms" sortOrder="0" parent="Magento_Backend::content_elements" action="cms/page" resource="Magento_Cms::page"/>
        <add id="Magento_Cms::cms_block" title="Blocks" module="Magento_Cms" sortOrder="30" parent="Magento_Backend::content_elements" action="cms/block" resource="Magento_Cms::block"/>
    </menu>
</config>

In the above code parent="Magento_Backend::content_elements" so it will display in the context menu so give a valid id to your menu then it will work.