Upgrades rarely fail - but when they do, the people who suffer are the ones who skipped the ten minutes of preparation. This page is that preparation: the backup, the recovery key, the space and the restore point, in order.
The upgrade itself keeps your files and apps by design. These checks are not about distrusting it - they are about the small chance of a power cut, a BitLocker prompt or a bad driver turning a routine job into a lost weekend. Ten minutes now covers every one of those cases.
An in-place upgrade is designed to keep everything, and it almost always does. "Almost" is why backups exist. Anything you cannot re-download - documents, photos, project files, office data - should exist in one more place before you start.
The bigger the upgrade, the more this matters: the enablement route barely touches your system, but the full ISO route rebuilds it.
If your drive is encrypted with BitLocker, an upgrade changes boot components - and a changed boot chain is exactly what makes BitLocker ask for its 48-digit recovery key on the next start. If that happens and you do not have the key, your data stays locked. There is no workaround and no support line that can unlock it.
manage-bde -protectors C: -get to see the key IDFeature upgrades fail most often for boring reasons. Setup needs working room on the system drive - keep at least 25 GB free for the full route - and it keeps a copy of your old Windows in the Windows.old folder afterwards, which takes space too. Run Storage Sense or Disk Cleanup first if the drive is tight. On a laptop, keep the charger connected from start to finish: a battery dying mid-upgrade is one of the few ways to turn a routine update into a recovery job. On a desktop, avoid starting during a storm or known power cuts.
Two minutes of insurance. Search for Create a restore point, open it, and create one manually - upgrades usually make their own, but a manual point is guaranteed to exist. Then run winver and note the version and build you are leaving (for example 24H2, build 26100). If anything misbehaves after the upgrade, that note tells you - and anyone helping you - exactly what changed. Finally, update your everyday apps and drivers before the upgrade rather than after: most post-upgrade problems are old drivers meeting a new Windows, and updating them first removes the clash.
Watch the video for the full upgrade once your checks are done - every setup screen, in order, with nothing skipped.
Watch Full VideoThe enablement package is one of the safest changes Windows makes - it flips features on and restarts once. A backup is still the right habit, but if any upgrade can be done with a light checklist, it is this one. The full ISO route is where a proper backup and image genuinely matter.
On most personal PCs it was backed up automatically to the Microsoft account used to sign in. Sign in to that account on another device and open its device recovery keys page. If it is not there and the PC will not boot past the key prompt, the data cannot be recovered - which is exactly why this check comes before the upgrade.
The enablement package needs very little. The full in-place upgrade wants at least 20 to 25 GB free on the system drive to work comfortably, and it keeps your previous Windows in Windows.old for the rollback period afterwards, so a nearly-full drive should be cleaned first.