I am getting 3 errors while building my game.

Error:Invalid command android
UnityEditor.HostView:OnGUI()

CommandInvokationFailure: Unable to list target platforms. Please make sure the android sdk path is correct. See the Console for more details.
C:/Program Files/Java/jdk1.8.0_121\bin\java.exe -Xmx2048M -Dcom.android.sdkmanager.toolsdir=“C:/sdk ools” -Dfile.encoding=UTF8 -jar “C:\Program Files\Unity\Editor\Data\PlaybackEngines\AndroidPlayer/Tools\sdktools.jar” -

stderr[
Error:Invalid command android
]
stdout[

]
exit code: 64
UnityEditor.Android.Command.Run (System.Diagnostics.ProcessStartInfo psi, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.Android.AndroidSDKTools.RunCommandInternal (System.String javaExe, System.String sdkToolsDir, System.String sdkToolCommand, Int32 memoryMB, System.String workingdir, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.Android.AndroidSDKTools.RunCommandSafe (System.String javaExe, System.String sdkToolsDir, System.String sdkToolCommand, Int32 memoryMB, System.String workingdir, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.HostView:OnGUI()

Error building Player: CommandInvokationFailure: Unable to list target platforms. Please make sure the android sdk path is correct. See the Console for more details.
C:/Program Files/Java/jdk1.8.0_121\bin\java.exe -Xmx2048M -Dcom.android.sdkmanager.toolsdir=“C:/sdk ools” -Dfile.encoding=UTF8 -jar “C:\Program Files\Unity\Editor\Data\PlaybackEngines\AndroidPlayer/Tools\sdktools.jar” -

stderr[
Error:Invalid command android
]
stdout[

]
exit code: 64

Thanks for answering but in fact it was the new sdk 2.3 which was not compatible with unity. I had to downgrade it to 2.2.

Someone had the same question on stack overflow

https://stackoverflow.com/questions/42538433/not-finding-android-sdk-unity