How to resolve this :Arduino UNO not working with Arduino wifi shield?
The error message you're getting "simply" means that the Arduino board isn't responding.

Regardless of the type of shield used, I've often seen this type of problems arise with power hungry shields, when the USB port is not able to provide enough current for both boards simultaneously (because of cheap cables, hub wich is not self-powered, ...).

A possible workaround (at least to test the validity of this answer) could be :


program the Arduino board without the shield attached
unplug the Arduino from USB
install the shield
plug from external power source with sufficient current rating
check that everything works.