"Unable to apply Update"

Try deleting the update file off the Edge and try downloading it again.

Delete Garmin\gupdate.gcd

I had the notice, but it didn't do anything until I had turned off the device, unplugged it from computer (battery 100%) and then turned on. The second time it updated. It also looked like there were at least 2 different components to the upgrade: touchscreen and "other", from watching the screen. I didn't see the "unable to apply update" message, but it did turn off unexpectedly the 1st time.

There is also a GPS update.

Thanks!
However, I tried now to delete / redownload the update several times, and still it does not want to do it. Also, it seems that only Garmin Express can find the update, If I try to update on the Edge itself wire WLAN, it does not even find any updates at all.
It's really weird. I wondered if it is wise to try some kind of factory reset, and then try the update? (at least if all settings could be backupped)

... on the other hand, the 4.00 update seems to be pretty horrible according to the other forum posts. Maybe I should not even try to fix this.

There is also a GPS update.

This seems to block other updates. Garmin Express told me there was a map update available but kept failing to install it. I disconnected the 1030 and restarted it, at point it said it was installing the GPS update, then once that was done Garmin Express was able to install the map update. As I posted in another post, Garmin Express also blocks when I try and update a CIQ field but it's in use on a page - Garmin Express doesn't seem to have any timeouts on operations which can never complete...

Okey. Interesting. I tried deleting / re-downloading / re-applying the update ~10 times now, and suddenly it worked. No idea why. (One thing I did do but cannot imagine that it had anything to do with it was deleting the empty custom map folder, and the startup up file with the custom start up message. That should not have any effect, but after doing that it worked....how knows...¯\_(?)_/¯ )

Updated yesterday, got the map update and touchscreen update but each time I now start Express it says that there is a update available (on my device I couldn't find the file GUPDATE.GCD only a file called GUPDATE.TMP?). Anyway Basecamp does see my device but after a few seconds it changes the name from Edge 1030 to GARMIN and sees it as a SD-card and I get a message that Basecamp can't find any detailed cards to work with and I need to update my GPS. Tried downloading the cards again (Europe) but nothing changed. Basecamp is worthless for me at the moment, worked before the update.

Went for a ride this morning with a gpx file uploaded from another source and was ok but my screen has become much less visible all of a sudden (normally on 30% now even on 100% not really good).

I downloaded and installed the previous version and choose under update preferences "never". Basecamp still doesn't work (doesn't see my card in my 1030.