If you use Magento 2.2.x and get the error like:

1 exception(s):
Exception #0 (Magento\Framework\Config\Dom\ValidationException): Element 'block', attribute 'class': [facet 'pattern'] The value '\Magento\Framework\View\Element\Text\ListText' is not accepted by the pattern '[A-Z][_a-zA-Z\d]*(\\[A-Z][_a-zA-Z\d]*)*'.
Line: 1187
Element 'block', attribute 'class': '\Magento\Framework\View\Element\Text\ListText' is not a valid value of the atomic type 'blockClassType'.
Line: 1187

Please find in all *.xml layout files string


and replace it with


(Remove slash from the beginning of the class attribute value)


If you get this issue on the blog post page, please do next:

1. Update blog extension to the min. v2.6.2
2. Check the file


for the class="\ that is described above and make necessary modifications.