5.1 lollipop – Android 5.1 Emulated abd push give adb: error: failed to copy etc… remote Read-only file system

Hi I’m not trying to change the system just upload some file to the /storage/sdcard folder or /sdcard i do

adb push etc /storage/sdcard

and I get

adb: error: failed to copy 'etc' to '/storage/sdcard/etc': remote Read-only file system

the thing is only happens on android 5.1 it must be a bug i read many post about remount the system but it is not the system what i need to remount it is the userdata partition it should be writable, i have create many times the AVD maybe it is something i did but always i get the same result

if i do df in shell i get

/dev                   498.4M    28.0K   498.4M   4096
/sys/fs/cgroup         498.4M    12.0K   498.4M   4096
/mnt/asec              498.4M     0.0K   498.4M   4096
/mnt/obb               498.4M     0.0K   498.4M   4096
/system                  1.4G     1.2G   180.2M   4096
/cache                  61.0M    56.0K    60.9M   4096
/data                    7.7G   571.6M     7.1G   4096

i can’t upload files , if i install es Explorer says the sdcard it is unmounted but don’t shows the internal storage where it is the internal storage ? some one can tell me please what it is happen here ?