I'm sorry to be so snarky, but as I've already asked you to provide more detail, I'll quote your signature here:

The way forward always starts with a minimal test.

Please, do provide us with a minimal example that we can use to reproduce your case. Also tell us what PSGI webserver you're using. Different webservers have different features and maybe the webserver your're using tries to be smart about sending files by delegating this task to the operating system by name.

Some of the tests seem to allow send_file( \$data, ... ), so maybe you're not filling $data properly in the GET case? A short example should help us help you better here.

In reply to Re^3: Dancer::send_file only for POST? by Corion
in thread Solved: Dancer::send_file doesn't work with POST? ( Angular JS hijacks the response) by 1nickt

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