incompatible character encodings: UTF-8 and ASCII-8BIT/2011-11-13 Askru post

This post on stackanswers.net aka Askru may offer some clues. I've translated the first answer, which seems useful, from Russian with Google Translate.

Translation

After doing some debugging, I found out that the problem occurs when using ActionDispatch :: a request object that happens to have strings that are all encoded in ASCII-8bit, regardless of whether my application is encoded in UTF-8 or not. I don’t know why this only happens when using a production server on Linux, but I will assume that this is some kind of ruby, or Rails, since I could not reproduce this error locally. The error occurred precisely because lines like this:

@current_path = request.env['PATH_INFO']

When this instance variable was printed in the Haml template, it caused an error because the string was encoded in ASCII-8bit instead of UTF-8. To solve this problem, I did the following:

@current_path = request.env['PATH_INFO'].dup.force_encoding(Encoding::UTF_8)

Which forced @current_path to use a duplicate string that was forced into the proper UTF-8 encoding. This error may occur with other data related to a similar request.headers request.