Unable to import computer.reg

All folders and programs (except registry editor) are closed. Windows 10 Pro. version 1803
I exported my entire registry, then tried to import it back. Result:
Cannot import C:\Users\jon\Desktop\regedit\RegEditBU\Computer.reg: Not all data was successfully written to the registry. Some keys are open by the system or other processes, or you have insufficient privileges to perform this operation.
(More in privileges later)
So I then exported the five individual HKEY's, and only HKEY_CURRENT_CONFIG was successfully imported back, "The keys and values contained in C:\Users\jon\Desktop\regedit\RegEditBU\HKCC.reg have been successfully added to the registry."
I then started playing with HKEY_CURRENT_CONFIG\Software\Fonts, changing LogPixels to 61 in the registry editor, exported it, and saw that the resulting .reg file reflected the change. Then in the .reg file I edited the 61 back to 60, and imported it back. The LogPixels was back to its original 60. So, I think I have proper privileges.
I followed the suggestion to perform an in-place repair with the installation disk that I used for the original installation. It was not successful, the only option available was to save NOTHING. Reasoning that there is probably a mismatch between my current installed version and the media version (bootable DVD), I downloaded the current version from MS. Then the in-place repair was successful.
I then exported the entire registry, but importing it back was still unsuccessful. So I exported the five KEYS individually, and only HKEY_CURRENT_CONFIG was successfully imported. So I tried the individual directories in HKEY_CURRENT_USER, and here's the result:

HKCUAppEvents.reg OK
HKCUConsole.reg OK
HKCUControlPanel.reg OK
HKCUEnvironment.reg OK
HKCUEUDC.reg OK
HKCUKeyboardLayout.reg OK
HKCUPrinters.reg OK
HKCUSoftware.reg Cannot import Error accessing the registry, then later Cannot import C:\Users\jon\Desktop\regedit\RegEditBU\HKCUSoftware.reg: Not all data was successfully written to the registry. Some keys are open by the system or other processes, or you have insufficient privileges to perform this operation.
HKCUSystem.reg OK
HKCUVolatileEnvironment.reg OK

I'm out of ideas.

"You can't import a whole registry with Windows running like that." Windows running like what?
I see that you're supposed to save your registry before making changes; export and import are not how to do it?

So basically, all my full registry exports are a waste of space and there is no use in saving them.

Ghot said:

As mentioned above... registry exports/imports are really only used for minor adjustments. For those times when you're making changes in the registry, that may damage/break Windows.

For saving the whole registry we use System Restore, or even better... a full OS image backup.

System Image doesnt work on Windows 10. I used both H1 and H2 and system image does not work.

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dalchina said:

N.B. Saving the registry alone and then restoring it after other system changes have been made can create inconsistencies. Think about it.


Automatically Create System Restore Point on Schedule in Windows 10
can be useful - I have one created daily on a schedule.

As for importing whole registry hives- well, you could do that offline: example:
Utilizing Offline Registry Editor to Repair the Registry

There used to be a feature called Regback in Windows where up to 5 copies of the registry were automatically saved. This can be enabled again.
Enable Automatic Backup of System Registry when Restart in Windows 10

Regback has value in very limited cases - e.g. when a PC is unbootable because of registry corruption, such that even if you have a System Restore point you couldn't run System Restore.

I created a restore point and exported the registry following each and every change I've made to Windows, so, when I back up I only go one step, losing the latest incorrect change only. This computer is offline and does not receive any updates at all unless I manually make the changes myself.