After renaming my file I am getting the following error when running the gulp build task:
Error: Error: File not found with singular glob: F:\Projects\xyz\HTML\app\css\main.css
at DestroyableTransform.<anonymous> (F:\Projects\xyz\HTML\node_modules\gulp-useref\lib\streamManager.js:90:36)
main.css file no longer exists as I changed it to style.css but for some reason it is searching for the old file.
As it turns out I missed changing file name in HTML file as it was calling main.css instead of style.css.
Changed it to:
An honest mistake but I believe someone else can run into something similar :)