magento 2 simple block firing exception Invalid template file

i’m new at magento 2 and i want to add some simple html to my header but i cant get to work, i have a simple theme that overrides blank theme from magento and i create the folder Magento_Theme and also this simple default.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configration.xsd">
  <referenceContainer name="header.panel"> <!-- the name of the container you want to insert into -->
    <container name="new_container" htmlClass="container_css_class" htmlTag="div">
      <block class="MagentoFrameworkViewElementTemplate" template="Magento_Theme::template/template.phtml" name="block_name" />
    </container>
  </referenceContainer>
</page>

and i have this simple template in the folder Magento_Themetemplatetemplate.phtml

<div class="block" style="float: right;">
 <?php echo __('Custom Line'); ?>
</div>

but the magento keep firing this error

1 exception(s):
Exception #0 (MagentoFrameworkExceptionValidatorException): Invalid 
template file: 'Magento_Theme::template/template.phtml' in module: '' 
block's name: 'block_name'

im using magento 2.2.5