Magento 2.1 – LogicException: Could Not Create an ACL Object on Admin Login

I had the same problem with my custom plugin and solved it. So just want to share how I solved it if anyone gets the same issue.

This was my error after logging in into admin dashboard:

1 exception(s):
Exception #0 (LogicException): Could not create an acl object: The XML in file "/home/magento2/app/code/Mycustommodule/Mymodulejs/etc/acl.xml" is invalid:
Element 'admin': This element is not expected. Expected is ( resource ).
Line: 5

Verify the XML and try again.

Exception #0 (LogicException): Could not create an acl object: The XML in file "/home/magento2/app/code/Mycustommodule/Mymodulejs/etc/acl.xml" is invalid:
Element 'admin': This element is not expected. Expected is ( resource ).
Line: 5

Verify the XML and try again.
#0 /home/magento2/generated/code/Magento/Framework/Acl/Builder/Proxy.php(95): Magento\Framework\Acl\Builder->getAcl()
#1 /home/magento2/app/code/Magento/Backend/Model/Auth/Session.php(227): Magento\Framework\Acl\Builder\Proxy->getAcl()
#2 /home/magento2/app/code/Magento/Backend/Model/Auth.php(165): Magento\Backend\Model\Auth\Session->processLogin()
#3 /home/magento2/lib/internal/Magento/Framework/Interception/Interceptor.php(58): Magento\Backend\Model\Auth->login('admin', '0omochl@1WA')
#4 /home/magento2/lib/internal/Magento/Framework/Interception/Interceptor.php(138): Magento\Backend\Model\Auth\Interceptor->___callParent('login', Array)
#5 /home/magento2/lib/internal/Magento/Framework/Interception/Interceptor.php(153): Magento\Backend\Model\Auth\Interceptor->Magento\Framework\Interception\{closure}('admin', '0omochl@1WA')
#6 /home/magento2/generated/code/Magento/Backend/Model/Auth/Interceptor.php(26): Magento\Backend\Model\Auth\Interceptor->___callPlugins('login', Array, Array)
#7 /home/magento2/app/code/Magento/Backend/App/Action/Plugin/Authentication.php(205): Magento\Backend\Model\Auth\Interceptor->login('admin', '0omochl@1WA')
#8 /home/magento2/app/code/Magento/Backend/App/Action/Plugin/Authentication.php(157): Magento\Backend\App\Action\Plugin\Authentication->_performLogin(Object(Magento\Framework\App\Request\Http))
#9 /home/magento2/app/code/Magento/Backend/App/Action/Plugin/Authentication.php(125): Magento\Backend\App\Action\Plugin\Authentication->_processNotLoggedInUser(Object(Magento\Framework\App\Request\Http))
#10 /home/magento2/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 /home/magento2/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 /home/magento2/generated/code/Magento/Backend/Controller/Adminhtml/Index/Index/Interceptor.php(26): Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor->___callPlugins('dispatch', Array, NULL)
#13 /home/magento2/lib/internal/Magento/Framework/App/FrontController.php(159): Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor->dispatch(Object(Magento\Framework\App\Request\Http))
#14 /home/magento2/lib/internal/Magento/Framework/App/FrontController.php(99): Magento\Framework\App\FrontController->processRequest(Object(Magento\Framework\App\Request\Http), Object(Magento\Backend\Controller\Adminhtml\Index\Index\Interceptor))
#15 /home/magento2/lib/internal/Magento/Framework/Interception/Interceptor.php(58): Magento\Framework\App\FrontController->dispatch(Object(Magento\Framework\App\Request\Http))
#16 /home/magento2/lib/internal/Magento/Framework/Interception/Interceptor.php(138): Magento\Framework\App\FrontController\Interceptor->___callParent('dispatch', Array)
#17 /home/magento2/lib/internal/Magento/Framework/Interception/Interceptor.php(153): Magento\Framework\App\FrontController\Interceptor->Magento\Framework\Interception\{closure}(Object(Magento\Framework\App\Request\Http))
#18 /home/magento2/generated/code/Magento/Framework/App/FrontController/Interceptor.php(26): Magento\Framework\App\FrontController\Interceptor->___callPlugins('dispatch', Array, Array)
#19 /home/magento2/lib/internal/Magento/Framework/App/Http.php(135): Magento\Framework\App\FrontController\Interceptor->dispatch(Object(Magento\Framework\App\Request\Http))
#20 /home/magento2/lib/internal/Magento/Framework/App/Bootstrap.php(258): Magento\Framework\App\Http->launch()
#21 /home/magento2/pub/index.php(37): Magento\Framework\App\Bootstrap->run(Object(Magento\Framework\App\Http\Interceptor))
#22 {main}

Problematic acl.xml file:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Acl/etc/acl.xsd">
    <acl>
        <resources>
            <admin>
                <children>
                    <system>
                        <children>
                            <config>
                                <children>
                                    <mycustommodule translate="title" module="Mycustommodule_Mymodulejs">
                                        <title>MyModule.js Options</title>
                                        <sort_order>1</sort_order>
                                    </mycustommodule>
                                </children>
                            </config>
                        </children>
                    </system>
                </children>
            </admin>
        </resources>
    </acl>
</config>

Then I've just modified it to:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Acl/etc/acl.xsd">
    <acl>
        <resources>
            <resource id="Magento_Backend::admin">
                <resource id="Magento_Backend::stores">
                    <resource id="Magento_Backend::stores_settings">
                        <resource id="Magento_Config::config">
                            <resource id="Mycustommodule_Mymodulejs::modulejs" title="MyModule.js Options" sortOrder="1" />
                        </resource>
                    </resource>
                </resource>
            </resource>
        </resources>
    </acl>
</config>

So on the end, it seems that the problem is that I was using an old AccessControlLists (acl.xml) structure from Magento 1 which is changed in Magento 2 and not accepted.

More info here in Mageplaza documentation - Magento 2 Admin ACL Access Control Lists