I am a newbie to Magento 2.2.4 and i want to get bootstrap 4 css and my own js files.. As a first step trying to override the theme layout file.

I created a theme and enabled it successfully. (All js and css call are routed to my theme). The theme is inherited from magento-blank theme

Now i am trying to override the parent blank theme with my theme layout following this guide https://devdocs.magento.com/guides/v2.2/frontend-dev-guide/layouts/layout-override.html

I am getting the following error :

Trying to override modular view file 'C:/xampp/htdocs/magento/app/design/frontend/TridentTechnominds/store/TridentTechnominds_Theme/layout/override/theme/magento/blank/default_head_blocks.xml' for theme 'magento/blank', which is not ancestor of theme 'TridentTechnominds/store'

I tried all methods like :

  1. theme/Magento/theme-frontend-blank/default_head_blocks.xml => getting error over here
  2. theme/Magento/frontend-blank/default_head_blocks.xml
  3. theme/Magento/blank/default_head_blocks.xml => getting error over here
  4. theme/magento/theme-frontend-blank/default_head_blocks.xml

Kindly guide me the right folder structure. I have been just making and googling for 6 hours now.

Attached is the folder structure...enter image description here

Update 1:

My mistake in naming convention of the folder. The blue underlined folder name was changed.

Even then, the trident.css is getting loaded from position black underlined i.e. under layout folder.

If i take it inside theme/magento/blank it doesnt work. Note: I tried Magento as foldername too.

Attaching the updated folder structure. enter image description here

2 Answers 2


To override layout from parent theme, here in your case default_head_blocks.xml from Magento/blank :


More information in Magento DevDocs.

  • I figured out the naming convention error. The folder name should be Magento_Theme but i gave as TridentTechnominds_Theme which caused the error. But still the theme is not overriding, but still i am getting the error. I will update my question shortly Commented May 24, 2018 at 5:59
  • 1
    Please try exactly my path
    – PЯINCƎ
    Commented May 24, 2018 at 8:10

Your theme should have the blank theme as the parent. app/design/frontend/TridentTechnominds/TridentTechnominds_Theme/theme.xml

<theme xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Config/etc/theme.xsd">
<title>TridentTechnominds Theme</title>

By using below structure in the theme you can do changes to the xml file of Magento_Theme module. app design frontend TridentTechnominds (namespace - recommends to use lowercase) TridentTechnominds_Theme (theme - recommends to use lowercase) Magento_Theme layout default_head_blocks.xml

If you want to override the file in blank theme itself use the structure mentioned in @Prince's comment below.

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