java.io.IOException: Server returned HTTP response code: 401 for URL: https://android.googleapis.com/gcm/sendPlease ensure that API_KEY has been replaced by the server API key, and that the device's registration token is correct (if specified).

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Samebug tips

  1. ,
    Expert tip

    Check if you didn't set RequestProperty Content-Type to the wrong type or if you're trying to send the wrong file to the server.

  2. ,

    401 means "Unauthorized", so there must be something with your credentials. You need to pass the authentication to let the server know its a valid user. Check whether the authentication details are provided.

Solutions on the web

via GitHub by IgorGanapolsky
, 1 year ago
Server returned HTTP response code: 401 for URL: https://android.googleapis.com/gcm/sendPlease ensure that API_KEY has been replaced by the server API key, and that the device's registration token is correct (if specified).
via Stack Overflow by celik
, 1 year ago
Server returned HTTP response code: 400 for URL: https://api.example.com/api-token-auth/
via Stack Overflow by Meriem.ZJ
, 5 months ago
Server returned HTTP response code: 400 for URL: https://www.googleapis.com/customsearch/v1?key=XXXX&cx=013036536707430787589:_pqjad5hr1a&q=the best universities&alt=json&num=10&start=1
via Stack Overflow by TDeveloper
, 7 months ago
Server returned HTTP response code: 403 for URL: https://www.googleapis.com/customsearch/v1?key=????&cx=013036536707430787589:_pqjad5hr1a&q=?????
via Stack Overflow by ThatGuy343
, 2 years ago
Server returned HTTP response code: 400 for URL: https://www.googleapis.com/urlshortener/v1/url
via GitHub by raghzz
, 2 years ago
Server returned HTTP response code: 400 for URL: https://americas.universal-api.pp.travelport.com/B2BGateway/connect/uAPI/HotelService
java.io.IOException: Server returned HTTP response code: 401 for URL: https://android.googleapis.com/gcm/sendPlease ensure that API_KEY has been replaced by the server API key, and that the device's registration token is correct (if specified).	at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1840)	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1441)	at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)	at gcm.play.android.samples.com.gcmsender.GcmSender.main(GcmSender.java:82)