adb no permissions error suddenly

Issue

I have been working on the Snapdragon Dragonboard for a few days now. I had been able to set it up and even push some applications onto it and run them. Needless to say, the commands adb shell and adb devices gave me some meaningful outputs. But today, I am not able to detect the device, adb shell gives me a no sufficient permissions error and adb devices gives me

????????? no devices

The instructions that I followed at the beginning of working with this board told me to include the line: 0x05c6; 0x0956 in the adb_usb.ini in the ~/.android folder.

However, I saw some better documentation today which asked me to include the line
SUBSYSTEM=="usb",SYSFS{idVendor}=="05c6",MODE="0666”
I replaced SYSFS with ATTR coz I read somewhere that the recent udev needs ATTR instead of SYSFS

I perform:

chmod a+r 51-android.rules
sudo stop udev
sudo start udev
android update adb
adb kill-server
adb start-server
adb devices

and I get the same result! Still no permissions. What is going wrong? Btw, the lsusb gives me a Qualcomm entry. When the usb is unplugged, the lsusb command does not give me a Qualcomm entry. How can the behavior change overnight?

Solution

Instead of:

adb kill-server

adb start-server

I tried:

sudo adb kill-server

sudo adb start-server

somehow this works. I dont know why.

Answered By - Spectre