I'm connecting to a phone on OpenSTF via adb. Running

$ adb connect <url>:<port_no>

produces the message

failed to authenticate to <url>:<port_no>

However, adb devices shows the device and I can interact as expected with the phone. What does the authentication failure mean and should it concern me?

2 Answers 2


If you're connected to the phone via USB, you may need to run

$ adb tcpip 5555

See https://developer.android.com/studio/command-line/adb#wireless

  • I can connect to it without problem. Oct 4, 2022 at 13:22
  • Could please write your environment?
    – Eagle
    Oct 5, 2022 at 14:59
  • Do you mean my environment variables or my OS info? Oct 5, 2022 at 15:05
  • I want to know how your phone is connected to your pc. Failed to authenticate message means that the phone doesn't provide permisstions to wifi debug - wifi adb
    – Eagle
    Oct 5, 2022 at 19:14
  • 1
    This command should be executed on the pc where the phone is connected. It is needed to open the debugging port
    – Eagle
    Oct 5, 2022 at 21:03

Looks like sometimes the adb tooling changes.

I doubt you have had an old adb running in background that was still connected but try adb kill-server.

A new connect failed but an old connection is still open.

As for me, the pubkey has to be renewed on STF sometimes so remove it from OpenSTF and add your adb pub key (~/.android/adbkey.pub) again (even or especially when it tells you the key already is registered!).

  • No, good. Same message. Sep 8, 2023 at 15:38

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