Every time I connect my wife's Edge Touring to the PC, Garmin Express syncs it without any problem and tells me that there is a map update available, but as soon as I ask it to update, the process starts, saying "Preparing device for map update", and terminates a few seconds later with a message in red saying "There was an error installing the update". The current version it is trying to install is Routable Cycle Map of Europe 2016.10, and Garmin Express is the current version (presently 4.1.21). There doesn't seem to be any log file produced giving any further information on the error. The SD card in the Touring has 8.8Gb free.
I've done a factory reset on the Edge Touring, but the problem persists.
I've tried performing the update on all three PCs that we have in the house, and it fails on all of them.
I can use Basecamp to install other maps downloaded from OpenFietsMap or Velomap onto the SD card without any problem.