Compilation from source on static-content deploy in magento 2.3.0 when upgraded from magento 2.2.2

Question

Hello i had upgraded magento 2.2.2 to 2.3.0 and i am getting following error when i do setup:static-content:deploy

Compilation from source: /home/xxxxxxxx/public_html/xxxx/xxxxxx/vendor/magento/theme-frontend-blank/web/css/styles-m.less
variable @button-primary__font-family is undefined in file /home/xxxxx/public_html/xxxxx/xxxxx/var/view_preprocessed/pub/static/frontend/xxxxx/xxxxx/en_US/css/source/lib/_buttons.less in _buttons.less on line 279, column 27
277|
278| .lib-button-primary(
279|     @_button-font-family: @button-primary__font-family,
280|     @_button-font-size: @button-primary__font-size,
281|     @_button-font-weight: @button-primary__font-weight,
282|     @_button-line-height: @button-primary__line-height, in _extends.less



In File.php line 150:

  The contents from the "/home/xxxxx/public_html/xxxxx/xxxxx/pub/static/frontend/xxxxx/xxxxx/en_US/css/styles-m.css" file can't be read. Warn
  ing!file_get_contents(/home/xxxxx/public_html/alpha/xxxxx/pub/static/frontend/xxxxx/xxxxx/en_US/css/styles-m.css): failed to open stream: N
  o such file or directory

Please help me

Answer 1

It looks like an issue with the CSS in your custom theme. Magento is unable to find the variables declared in variables/_buttons.less.

You can check if you're overwriting the file in app/design/frontend/NAMESPACE/THEME/web/css/source/variables/_buttons.less

If your theme is overwriting the file, you'll need to make sure your CSS has all the variables declared that Magento requires.

//  Primary button
@button-primary__font-family: @button__font-family;
@button-primary__font-size: @button__font-size;
@button-primary__font-weight: @button__font-weight;
@button-primary__line-height: false;
@button-primary__width: false;
@button-primary__margin: false;
@button-primary__padding: @button__padding;
@button-primary__gradient: false;
@button-primary__gradient-direction: false;