As I researched, this could be caused by something that is intercepting your request, and sending an empty request.
Possibly an ad blocker (such as AdBlock) as indicated in this SOEN response:
link
Tip: Try installing fiddler to see how the request is getting, because there must be something intercepting the request ... after doing this, try to check in other browsers, and see how the requests stay in each of the browsers ... so you can isolate the problem more and more.
EDIT More suggestions based on SOEN:
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Start chrome with --disable-extensions
on the command line ( link )
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Verify that the request is not being made to another domain
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Feature is being loaded from the browser cache ( link ) ... eg for lack of connectivity to the server, the browser takes a resource from the cache, without actually requesting it.