A used iPhone may show an update prompt as soon as you sign in. Avoid starting it while leaving home or still transferring data. Apple says an update normally preserves data and settings, but a backup, free space, stable power and network remain important preparations, especially on a newly purchased device.
1. Confirm the model and offered version
Open Settings > General > Software Update to see the installed version and available update. Apple publishes compatible-model lists for major iOS versions; confirm your exact model under Settings > General > About. Not every older iPhone receives the same newest release, and availability can change over time.
If a listing says only “iPhone 13” or “iPhone 15 Pro,” inspect the actual phone and its current system version at handover. Software support matters, but do not turn it into a promised number of future update years without manufacturer confirmation.
2. Make and verify your backup
Apple recommends backing up before an update. You can use iCloud or a computer. For iCloud, open Settings > your name > iCloud > iCloud Backup, choose Back Up Now and check the completion date and time. If iCloud lacks space, address that or choose another backup route before starting.
If a just-purchased phone still contains another person’s data, do not update it to preserve their account. Complete the handover, ensure Activation Lock is removed and set up your own Apple Account before adding personal data.
3. Leave free space and time
Settings > General > iPhone Storage shows available space and large apps. An update needs room to download and install; the amount varies by release. Apple may suggest offloading unused apps, or you can remove content you have backed up, but understand what you are deleting first.
Use stable Wi-Fi, connect to power and pick a time when you do not urgently need the phone for calls, one-time codes or work. Progress can take time depending on the package and device; do not restart merely because the bar pauses briefly.
4. Read the failure before trying a fix
Not enough space, inability to contact the server, slow downloading and unsupported software require different responses. Apple explains trying another network, deleting a downloaded update to fetch it again, or using a computer when needed. Change one thing at a time and retain your backup.
If the phone loses power, overheats unusually or remains unresponsive, follow official support guidance or ask a technician to inspect it. Avoid unknown repair software or an erase-all action before confirming that your backup can be used.
5. Factor updates into a used-phone purchase
TECHBUY lists the used iPhone 13 and used iPhone 15 Pro. At publication, Apple includes both in its iOS 26 compatibility list, but confirm the update offered and actual experience on the listed unit. Price and storage vary by variant.
At handover, inspect battery, storage, account status and your own backup before updating. A used iPhone is worth considering for its condition and working essential features, not solely because it can install an iOS release.
Conclusion
A safe update starts with the right model, a usable backup and suitable installation conditions. Sources: Apple’s iPhone update guide, update troubleshooting and the iOS 26 compatibility list.
