On occasion, your Duo hardware fob device might become out-of-sync with what Duo expects. The symptoms of this is the frustrating, "Invalid code" message and the failure of your login attempt. It is easy to fix, however.
The main reasons for your Duo fob device getting into an out-of-sync status is that the green button has been, usually unintentionally, pressed a good number of times from, for example, being jumbled around inside a bag or pocket (see https://help.duo.com/s/article/3494 and https://help.duo.com/s/article/2240.)
To fix this:
- Go to a Duo-challenged login page, for example, canvas.mines.edu.
- Input your username and password, as normal.
- At the Duo-challenge screen, press your fob's green button and input the six-digit code. This will, according to the symptoms you've already seen, fail.
- Repeat step 3) a few more times, in quick succession. Please allow the device to power-off the display (after about 15-20 seconds or so) before re-pressing the green button for the next value. This repetitive step shouldn't need to be done more than two or three times. However, if it continues showing you failed attempts after attempt number five, please open a Helpdesk ticket and ITS will help you resolve this.
- After a few attempts it should work again. This is because this process makes Duo, on the back-end, rescan it's synchronization range with your fob device.
- Everything is now back in-sync and working as intended.