Couple of notes.
vapvap, your address has library twice, which resulted in an error in my case.
With the address:
https://www.your-domain.com/wp-content/themes/arras-theme/library/cache/
I could generate an index, which had two links, one of which was parent directory.
I could not find anything there that could be 777 or reset to 777. Thanks in advance for any help.
