ActionView::Template::Error (incompatible character encodings: UTF-8 and ASCII-8BIT)

After doing some debugging I found out the issue occurs when using the ActionDispatch::Request object which happens to have strings that are all coded in ASCII-8BIT, regardless of whether my app is coded in UTF-8 or not. I do not know why this only happens when using a production server on Linux, but I'm going to assume it's some quirk in Ruby or Rails since I was unable to reproduce this error locally. The error occurred specifically because of a line 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 I did the following:

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

Which forced @current_path to use a duplicated string that was forced into the proper UTF-8 encoding. This error can also occur with other request related data like request.headers.

Mysql could be the source of troublesome ascii. Try putting the following in initializer to at least eliminate this possibility:

require 'mysql'class Mysql::Result  def encode(value, encoding = "utf-8")    String === value ? value.force_encoding(encoding) : value  end  def each_utf8(&block)    each_orig do |row|      yield row.map {|col| encode(col) }    end  end  alias each_orig each  alias each each_utf8  def each_hash_utf8(&block)    each_hash_orig do |row|      row.each {|k, v| row[k] = encode(v) }      yield(row)    end  end  alias each_hash_orig each_hash  alias each_hash each_hash_utf8end

edit

This may not be applicable to mysql2 gem. Works for mysql however.