I came across this error while running my rails server

[2014-02-04 20:31:12] WARN  Could not determine content-length of response body. Set content-length of the response or set Response#chunked = true

[2014-02-04 20:31:12] WARN  Could not determine content-length of response body. Set content-length of the response or set Response#chunked = true

[2014-02-04 20:31:12] WARN  Could not determine content-length of response body. Set content-length of the response or set Response#chunked = true

[2014-02-04 20:31:12] WARN  Could not determine content-length of response body. Set content-length of the response or se

This is a problem of Webrick. you can use "Thin" instead.

Add this to Gemfile

gem 'thin'

then rails s will use thin instead of Webrick, and the warn will disappear.

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