For apps/android_rpc and apps/android_deploy, gradle clean build will cause such an error.
Caused by: java.io.IOException: Cannot run program “ndk-build” (in directory “/home/lvhang/tvm/apps/android_rpc/app”): error=2, No such file or directory at net.rubygrapefruit.platform.internal.DefaultProcessLauncher.start(DefaultProcessLauncher.java:25)