i am getting this error on developer mode but works in default

Exception #0 (Magento\Framework\Config\Dom\ValidationException): Theme layout update file XML declaration allowed only at the start of the document Line: 31 First line xml, is line 31 before that its html comment

<?xml version="1.0" encoding="UTF-8"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="admin-2columns-left" xsi:noNamespaceSchemaLocation="../../../../../../../lib/internal/Magento/Framework/View/Layout/etc/page_configuration.xsd">
     <update handle="editor"/>
       <referenceContainer name="content">
            <block class="Apptha\Airhotels\Block\Adminhtml\Uploadvideo\Edit" name="airhotels_uploadvideo_edit"/>
         <referenceContainer name="left">
            <block class="Apptha\Airhotels\Block\Adminhtml\Uploadvideo\Edit\Tabs" name="airhotels_uploadvideo_edit_tabs">
                <block class="Apptha\Airhotels\Block\Adminhtml\Uploadvideo\Edit\Tab\AddVideo" name="airhotels_uploadvideo_edit_tab_addvideo"/>
                 <action method="addTab">
                    <argument name="name" xsi:type="string">addvideo_section</argument>
                    <argument name="block" xsi:type="string">airhotels_uploadvideo_edit_tab_addvideo</argument>


1 Answer 1


I moved the xml declaration at the top of the page and its working now. Leaving this here if someone else have same issue.

  • Just FYI ... you can also mark your own answer as accepted.
    – sv3n
    May 27, 2019 at 9:16

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