I'm working with a set of Less CSS files I didn't write in Magento 2. During compilation, I get the following error

Compilation from source: 

Compilation from source: 
#0 /path/to/magento/framework/View/Asset/PreProcessor/AlternativeSource.php(155): Magento\Framework\Css\PreProcessor\Adapter\Less\Processor->processContent(Object(Magento\Framework\View\Asset\File))

I know I can start debugging from line 155 in AlternativeSource.php -- but does anyone know what this cryptic error means?

1 Answer 1


I think this may happen because the generated CSS content is empty.

See: https://github.com/magento/magento2/blob/f748e57d04f65cb0b6f3d22cfc00602e6772e51d/lib/internal/Magento/Framework/Css/PreProcessor/Adapter/Less/Processor.php#L92.

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