内部错误：无效的UTF-8 - Sass＆Gulp

Question

I get the following error when trying to run gulp sass in Linux Ubuntu

hutber@hutber-ubuntu:/var/www/beta.norsemanfc.co.uk$ gulp sass
[14:43:26] Using gulpfile /var/www/beta.norsemanfc.co.uk/gulpfile.js
[14:43:26] Starting 'sass'...
[14:43:27] gulp-notify: [Compile Error] frontend/sass/style.scss
Internal Error: Invalid UTF-8

[14:43:27] Finished 'sass' after 547 ms

Searching through all the files/folders for any special characters returns nothing.

hutber@hutber-ubuntu:/var/www/beta.norsemanfc.co.uk$ find ./* -iregex '.*/.*[èö].*' -print

Otherwise if I remove the @import at the start of the file it will then fail on the @include border-box-sizing; as this is a variable from susy

So of course how can I get sass running locally?

updated

hutber@hutber-ubuntu:/var/www/beta.norsemanfc.co.uk/frontend/sass$ find ./* | xargs grep -i '.*/.*[èö].*'
grep: ./fonts: Is a directory
grep: ./fonts/helvetica-neue: Is a directory
grep: ./modules: Is a directory
grep: ./modules/form: Is a directory
grep: ./pages: Is a directory
grep: ./plugins: Is a directory
grep: ./susy: Is a directory
grep: ./susy/susy: Is a directory
grep: ./susy/susy/language: Is a directory
grep: ./susy/susy/language/susy: Is a directory
grep: ./susy/susy/language/susyone: Is a directory
grep: ./susy/susy/su: Is a directory
grep: ./susy/susy/output: Is a directory
grep: ./susy/susy/output/support: Is a directory
grep: ./susy/susy/output/float: Is a directory
grep: ./susy/susy/output/shared: Is a directory

NB: Similar Question: Error "Invalid UTF-8" when compiling sass with @import This is fixed by removing special charaters from the path, however all my folders are english and always have been.

Answer 1

You can try converting the file to ASCII and see if ? marks appears, those are the non UTF-8 ones:

cat your-file.css | iconv -f utf-8 -t ascii//TRANSLIT > ascii.css