I'm not sure which sub-forum this should go on so, mods, feel free to move. I have two Toshiba Satellite laptops, one old, one new, both running Win 10 Home installed via the recent upgrades.
Until yesterday, 12/09/15, I used to be able to do a "File History" backup from the new laptop to a WD Ext HDD 1021 USB Device (a 4TB unit). I also backup my Norton to that drive, AND, I also backup from the old laptop to the same drive (both Norton and File History).
To avoid confusion among the two computers' backup files (backups can only be done to the HDD, not specific folders on it), I move the backup-generated files and folders into named user folders. After each backup, I would delete the old contents of each user folder, and replace them with the new backup items.
Yesterday, there was a Windows Update (details of which I mention below in case they are relevant). I also did both a Norton backup and a File History backup from the new laptop to the 4TB Ext. HDD. To save time (why do I always do these things?) while one backup was running (being a thicky, I can't remember which) I deleted the "other" backup content from the relevant user folder. (i.e., if it was a File History backup I was running, then I was deleting the Norton items. If a Norton backup was running, then I was deleting the File History folder).
Either way, a box pops up saying two actions are running simultaneously and shows them. Then one stops - I didn't notice which one.
Afterwards, I noticed the File History backup hadn't apparently succeeded as the "Last Backup" date was in August. I tried to run it and found I couldn't. A bit more investigation and I realised my new laptop's Win 10 wasn't recognizing the 4TB HDD as a "usable drive" now. After a few shutdowns and reboots (always turn it off and on - sometimes works) and a bit more investigation (see attached pdf below with screenshots) the situation's the same.
NB - I can still - no probs - backup Norton to the 4TB HDD, and File History will recognize my old HDD (WD My Pavilion) and backup to that. It recognized and tried backing up to a usb stick also.
Re the Win update (new laptop) - it had seemed a bit funny - UPDATE HISTORY shows:
Windows Malicious Software Removal Tool for Windows 8, 8.1, 10 and Windows Server 2012, 2012 R2 x64 Edition - September 2015 (KB890830) Successfully inastalled 12/09/15 (after hiccup) and...
Cumulative Update for Windows 10 for x64-based Systems (KB3081455) Twice failed to install 12/09/15, PBOBABLY BECAUSE it had successfully installed 9/09/15!
(1) was it me and my stupidity in running those two actions together? (and maybe killing a registry entry or a Win 10 system file?) Or could it have been the Win 10 download? AND, of course,
(2) how can I get my new laptop/Win 10 to again recognize a previously recognized HDD? All is not lost if a solution can't be found - after all, I am still allowed to backup to the old HDD. COMMENT, The only difference I could see is the old WD HDD is FAT32 and the new 4TB one is NTFS. Still, it used to run ok.