Magento 2 How to resolve error: Unable to find a physical ancestor for a theme?

Question

When trying to install 'TemplateMonster Theme'I get the error on the frontend:

"Unable to find a physical ancestor for a theme 'TemplateMonster Theme'.","1":"#0 \/lib\/internal\/Magento\/Framework\/View\/Model\/Layout\/Merge.php(713):"

In the same moment backend of the site working.

I do all steps required in the install guide but that's guide not helped me.

So I think maybe I missed something and tryed to use theme dump which I find in the 'TemplateMonster Theme' folder. And unsuccessfull...

The only way to displayed my magento2 site it's switch back to the default theme.

Little notice - my current magento site version is 2.2.5, theme demo site works perfect on the version 2.0.2.

P.S. I'm allready read same post and that's not helped me:

For any tips I will be very grateful!!!

Answer 1

For me the cause of the problem was the database. I check type and theme_if of my themes and then $UPDATE theme SET type=0 WHERE theme_id IN (4, 5);

Look also in this anwser Magento 2 Unable to find a physical ancestor for a theme