I too have problems upgrading - I get error 262 at the beginning of the flashing. When I restart the MTeoR it starts WM as usual, so it seems it hasn't started flashing yet. This happens on two different computers. Any suggestions, please?
Note: I am able to flash 18.104.22.168 with any of the above computers. Only the new 1.34 is a problem. Could the install program be faulty? If so, it is pretty bad considering it is an official release.