I installed the android sdk and downloaded tools to fix errors but this error seems to be the one I cant seem to fix. it occurs when I attempt to build and its really annoying me now
I had the same problem, and the only thing that fixed it was by replacing the tools folder with the updated one. The original tools folder that comes with the Android Studio download doesn’t work with Unity well, so I had to download the updated tools folder (here: http://dl-ssl.google.com/android/repository/tools_r25.2.5-windows.zip). Then, I deleted the original folder and extracted the new one to the Android SDK root, and it worked perfectly. Hope that helped!
I had that problem. In my case, Android SDK path in Unity was wrong (Edit/Preferences/External Tools). When I copy correct path from Android Studio, it works! Try that. Good luck!