Can't upgrade firmware past 1.1.8

[Thomas]

ERROR:goTenna.driver.Driver:SDK not supported, not X-Device product pro!
ERROR:goTenna.driver.Driver:Error during device handshake

I get similar errors like the users in this thread:

USB SDK Installation

Hi, I have just installed the latest build of the Python SDK, posted today, and can confirm the installation problems are fixed. But I am still having problems with the sample.py script. It still reported the goTenna Mesh as a “Pro” device when I connect, although I the script is connecting to the goTenna, as it reports the correct serial number (I have checked with two different devices). When I run the set_guid device, I now get a different error message: goTenna>ERROR:goTenna.driver.Driv…

But the suggested fix (upgrading to 1.1.12) is not available anymore:

USB SDK Installation

Hi Pete94, Please upgrade your mesh unit to firmware version 1.1.12 by following the instructions provided in Mesh Firmware Upgrade to 1.1.12.pdf

Please help