Error 404 On Post Update (word -> from)

When i’m trying to update a post with the word “from” in the post/page content this is returning me ERROR 404 (from the template).

Website url shows: example.com/wp-admin/post.php (with 404 error inside template)

PHP Version: 5.5

I think my hosting provider changed yesterday the php version from 5.4 to 5.5, because before i haven’t got this error.