Many thanks dariosalvi, I followed your procedure and got the exact screen printout as yours in upgrading the shield. However when I put the shield back and tried the WiFiUdpNtpClient, I didn't get the same result, looks like that I can't connect to the server. What I discovered is that the router returned an IP address of 0.0.0.0, then I used the scanNetworks sketch to check on the router I used. What I found is that this sketch showed my shield's MAC address is 0:0:0:0:0:0 ! As I remembered my shield MAC address was some number other than all zeros! Does that mean I eraseed the MAC address also during the upgrade? Anyone has the same problem? Help please!