Content-length error prevents page load and leads lint error

[kakubei]

I get this error always:

Unexpected error while processing request: Content-Length header was 1747, but should be 1757
/Users/alexd/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/lint.rb:631:in `verify_content_length'

If my post is very small, I get it with some types of characters like " but they are all UTF-8 plain text.

When I fix all the character issues, I still get the error when trying to display the whole post.