Rack error: bad body content


I get an error like the following.

/!\ FAILSAFE /!\ 05/27/2010 12:50
  Status: 500 Internal Server Error
  bad content body

It happens when I update a page with images.
This doesn't happen on development server though.
So it might be rack version related.

My development server has rack 1.0 bundled.
The production server has rack 1.0.1.
Both are rails 2.3.2.

Any idea how to fix this problem?