Force restart (Volume Up, Volume Down, hold Side). If it still sticks, connect to a Mac or PC, enter Recovery Mode and choose Update (not Restore) to reinstall iOS while keeping data. Only use Restore if Update fails, since that erases the iPhone.

The short explanation

During startup iOS checks and loads the system. A corrupted update, nearly full storage or a migration that didn’t finish can stop it at the logo. During a progress-bar update, the logo can legitimately stay up for a long time. Wait an hour if the bar is moving.

Symptoms

  • Apple logo stays on screen indefinitely.
  • Restarts over and over (boot loop).
  • Logo with a progress bar that doesn't move.

Common causes

  • Interrupted or failed iOS update.
  • Storage almost full.
  • Data transfer interrupted.
  • Hardware fault (less common).

Try these fixes

  1. Wait if there's a progress barGive it up to an hour with the iPhone charging.
  2. Force restartPress and release Volume Up, then Volume Down, then hold the Side button until the screen goes off and the logo reappears.
  3. Update in Recovery ModeConnect to a Mac (Finder) or Windows PC (Apple Devices app or iTunes). Do the same button sequence but keep holding Side until the recovery screen appears. Choose Update.
  4. If it exits recoveryDownloads over 15 minutes cause it to exit; repeat the button sequence and choose Update again.
  5. Restore as a last resortChoose Restore (erases data), then restore from backup.
  6. Get serviceIf Restore fails or it loops after restoring, contact Apple. It may be a hardware issue.
Check it's fixed: The iPhone reaches the lock screen and stays on.

Avoiding it in future

Keep at least a few GB free and leave the iPhone plugged in during updates.