What you’re seeing
- Time Machine shows "Time Machine couldn't complete the backup" or "The backup disk could not be found".
- The last successful backup date is weeks old even though the NAS is online.
- Time Machine reports it must create a new backup because the existing one could not be verified.
- Backups to a USB drive work, but backups over the network to Synology, QNAP or another NAS keep failing.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- The NAS share no longer advertises itself as a Time Machine destination after a firmware update.
- SMB protocol or encryption settings on the NAS do not match what the current macOS version expects.
- The sparse bundle on the NAS has become corrupted after interrupted backups or power loss.
- The NAS quota or volume is full, so new backups cannot be written.
- Mac sleep, Wi-Fi drops or VPN connections interrupt long backups before they can finish.
- The NAS account password changed, and the Mac is still using old saved credentials.
Why it matters
A failing backup is invisible until the day it is needed. If a Mac is lost, stolen or hit by ransomware, a backup that silently stopped weeks ago can mean losing weeks of client work, financial records and email. When Time Machine discards an existing backup to start over, the history of older file versions is gone too. For small businesses that rely on a NAS as their main safety net, this is a serious gap in business continuity.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
Are our old backups still usable?
Often yes, but if Time Machine says the backup could not be verified, older history may be at risk. It is worth checking before anything is deleted.
Why does USB work but the NAS doesn't?
Network backups depend on the NAS software, SMB settings and a stable connection, so there are more points of failure than with a directly attached drive.
Can you check both the Mac and the NAS?
Yes, a certified US engineer reviews both through a remote secure session, and you pay only when backups are completing again.