There is a slight problem in Rack 1.0.0 that causes a fatal error to be produced when uploading files <= 110K in size. You may need to patch Rack if you see the following error when uploading a file (I saw it with Paperclip):

Here's what you do to patch Rack:

You should now be back in business. Hopefully it won't be too long before an update is released for Rack that includes the patch.

Happy uploading!

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