The error pops up on https://stevelitchfield.rf.gd/sshow/chat.html - which worked yesterday and which I can see and change happily via FTP.
I’m still feeling my way into infinityfree, hopefully this isn’t a FAQ. Or maybe it’s a cache glitch of some kind?
I’m sorry, but this is by design. The “chat” keyword is blocked because we do not allow live chat scripts to be hosted with us.
This is actually covered in the article about 403 errors: Redirected to InfinityFree 403 Forbidden page
So unless the file was actually called something else before, I’m more surprised that it worked yesterday than that it doesn’t work now.
It’s not a chat page. It just has the word ‘chat’ in the text! 
So if I reword it slightly then it will work?
It’s also in the article actually, but yes, if you rename it it should work again.
OK, I renamed the file to not have ‘chat’ in the filename and I also removed the H1 title that had that word in and it seems to work now, thanks. https://stevelitchfield.rf.gd/sshow/psc.html