Rare flash memory timing issue. Fix: Wait 10 minutes. If no change, power cycle the DVR. It may have completed silently. Check the version. If bricked, you may need a recovery image (contact tech support).
Does your DVR randomly reboot? Do playback timestamps glitch? Do motion detection alerts trigger without movement? These are likely firmware bugs. Each includes a changelog listing squashed bugs, leading to 24/7 operational stability.