Q:

Magento 2 UI component- Element argument is not allowed here

After upgrade to Magento 2, in IDE PhpStorm, the UI component file show a lot of errors , like Element argument is not allowed here, Element xxx is not allowed here etc. 
But, the UI component file is working well in system.  And the official UI component file also has the errors.  Like cms_block_listing.xml:

How to fix it? 

A:

Go to File > Setting > Plugins > search text ('Magento2'); install this plugin after that click regenerated urn map and reindex in Magento2 Plugin config .  Good luck!