Error: Can't set headers after they are sent.

[sdantuoni]

Buenas, soy algo nuevo en NodeJS y tengo este error. A que se puede deber?

Código:

Error: Can't set headers after they are sent.
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:356:11)
    at ServerResponse.header (/Users/santiago/Documents/license/node_modules/express/lib/response.js:719:10)
    at ServerResponse.send (/Users/santiago/Documents/license/node_modules/express/lib/response.js:164:12)
    at ServerResponse.json (/Users/santiago/Documents/license/node_modules/express/lib/response.js:250:15)
    at /Users/santiago/Documents/license/license-server/app/routes/apiLicenses.js:32:10
    at DestroyableTransform.<anonymous> (/Users/santiago/Documents/license/license-server/app/models/licenses.js:52:4)
    at emitOne (events.js:96:13)
    at DestroyableTransform.emit (events.js:188:7)
    at /Users/santiago/Documents/license/node_modules/gh-api-stream/index.js:55:30
    at /Users/santiago/Documents/license/node_modules/got/index.js:186:6

[starfix]

Ya se enviaron o establecieron las cabeceras de la respuesta al cliente y se están intentando establecer nuevamente.

[Carlangueitor]

Es claramente un error de tu código.

Saludos