failed to find target with hash string android-23
Solution 1:
In my case, clearing caché didn't work.
On SDK Manager, be sure to check the box on "show package descriptions"; then you should also select the "Google APIs" for the version you are willing to install.
Install it and then you should be ok
Solution 2:
In Android Studio File -> Invalidate Caches/Restart
solved the issue for me.
Solution 3:
The answer to this question.
Gradle gets stupid from time to time and wiping out the cache is the only solution that I've found. You'll find a hidden .gradle folder under your user home folder and another one wherever the checkout location is for osmdroid.