Hi,
How much space you need to upgrade to the 1903 is dependent upon how you do it.. If you do it through Windows Update or the Create Media... Install Now... method, it takes much more space... The reason being is he way it is downloaded and created... The
needed files are downloaded... THEN converted to installation files and\or a ISO... This can easily take up nearly 8GB all in itself... Then there is the issue of the "Old" windows being saved in the Windows.old folder.. This can be deleted, but not until
after the fact..
If you manually upgrade from a ISO on a flash drive or external HDD, you will not need that extra 8GB of space...
I think the spec sheet you mentioned is regarding a "Clean Install", and what the installer will accept for drive size.. An upgrade is a entirely different ballgame due to the already existing files... The only thing I can suggest is to be sure the "Windows.old"
folder has been removed... That is the largest offender by far...
When you say the OS is taking up 27GB of space, I would guess that a large part of that is the result of a couple of hidden files on C:\.. The PageFile.sys and Hiberfil.sys.. The pagefile is for memory overflow, and the hiberfil is for Hibernation type storage
and the functioning of Fast Startup...
Both can be turned off temporarily to free up space... The Pagefile can also simply be reduced in size as well..
At times I remove these files to clean up my OS drive with a defrag... Then turn them back on when it is finished... I have had no ill effects from this... But with only 1GB of memory available, you may want maybe just reduce the size of the Pagefile, or
leave it alone...
I didn't check the sizes before replying, so I can't be more specific at the moment...
You can turn off the Hiberfil.sys by entering the command Powercfg -h off into a Command Prompt or Powershell as Admin.. The turn it back on with Powercfg -h on...
You can show the hidden folders\files through "Folder Options"... View tab..
For the Pagefile, right click on This PC.. Properties.. Advanced System Settings... Performance-Settings button... Advanced Tab again, the "Virtual Memory" at the bottom..
As far as the ISO is concerned... I unplugged the flash drive during the first restart... By the time of the restart, all of the needed files have already been copied to the internal drive..
I do not actually know if you can manage an upgrade to 1809 or 1903... As suggested by Dave, your best bet may be to switch to 32 bit, but that may bring up issues with drivers and such..
The upgrades have access to preinstalled HP drivers, a clean install may not... You might check with HP and see what is available as far as a switch to 32 bit... They may have a 32 bit version of their preinstalled Windows available...