Build Project to Android Error: Unable to start ADB server.

@Samuel014 Hi, I solved this error just yet! it caused by overlap between the two adb.exe : one at the SDK folder that you instruct Unity to search, the other one at your phone's driver folder-->remove this one! Then you can use cmd to check if the right adb.exe is detected. you can see the figure that I attached. Hope this is useful to you.

My solution was to close my android emulator, Nox.

Took me a very long time to realize I just needed to close it :)

My issue appears to be that the ADB server is not starting up automatically... or that the wrong one is starting. I'm not yet sure which.

Unity tools will install its own Android toolset.

My resolve was to: - open the Windows console as admin (cmd... run as admin) - type the following: "C:\Program Files\Unity\Hub\Editor\2019.2.3f1\Editor\Data\PlaybackEngines\AndroidPlayer\SDK\platform-tools\adb.exe" kill-server - type the following: "C:\Program Files\Unity\Hub\Editor\2019.2.3f1\Editor\Data\PlaybackEngines\AndroidPlayer\SDK\platform-tools\adb.exe" start-server

Note that your path to adb may be different.

Thanks for the replies. I tried all of it but keep getting the same error in the command prompt: "adb server version (39) doesn't match this client (40); killing... could not read ok from ADB Server * failed to start daemon error: cannot connect to daemon", I really don't know what this means. I'm only 14 years old but I did build a game and know how to code, but I barely understand anything about all the other stuff on how to set it up like what SDK's and ADB and all of this is. So now I'm trying to build my game for an Android tablet so I can test it of course. But like I said above, I keep getting the same errors, and when I look them up, I can't find anything to solve it. So does anyone know a detailed tutorial or something on how to do this or on how to solve this errors?

I was able to solve the problem by closing Unity, connecting the android device, restarting Unity, enter play mode once, exit playmode and then build and run to the device.

Seems the 2019.3 release version is still a bit buggy.

EDIT: In the end it was also the HTC manager, that was installed by my phone, that started up it's own ADB server, instead of the Unity ADB server. Deleted the HTC Sync Manager and all was working normally again. To find to out if there is another adb starting up, just plug your phone into the PC (with Unity closed) and check the Task manager for a running adb.