ServiceStack/ServiceStack — pull request #553 by inhibition (2013-03-28 05:34:32+00:00)
Title: Response should be 204 No Content for void methods.

It appears that the 204 response behaviour added to IHttpResponseExtensions.cs in commit 80c90cc42b1c2d2352a3f3593915230ddd4671e0 was subsequently removed in cb4e6456b7f6618adcf8ec07eee430f9225f2e1a.

Changing this back to invoke httpRes.EndHttpRequestWithNoContent() resolves the issue.