Mac Prohibitory Sign on Startup – Data Recovery
Your Mac shows a circle with a line through it (prohibitory symbol) on startup.
The prohibitory sign means your Mac found a drive with macOS, but that macOS is incompatible or corrupted. Unlike the question mark folder (can't find any OS), this means it found something but can't use it. Your data is usually intact.
Don't Reinstall macOS Yet
- ×Do not reinstall macOS over the existing system
- ×Do not erase the drive in Recovery Mode
- ×Do not use Internet Recovery without backing up first
- ×Do not downgrade macOS trying to fix it
- ×Do not reset NVRAM repeatedly
Why this matters: The prohibitory sign is an OS problem, not usually a data problem. Reinstalling over it risks overwriting your files. Recover data first if it's important.
Most Likely Causes
macOS Corruption
System files are corrupted and macOS can't boot properly.
Incompatible macOS Version
The installed macOS doesn't support this Mac model (common after migrations).
Security Settings Conflict
T2 security chip or SIP settings preventing boot from this installation.
Partial Drive Failure
The drive is working but has damaged areas affecting system files.
Safe Diagnostic Checks
These checks are non-destructive and safe to perform. Follow them exactly as written.
Try Safe Mode
- Shut down Mac completely
- Turn on and immediately hold Shift
- If Safe Mode boots, system files may be repairable
- If not, likely deeper corruption
- Don't make changes in Safe Mode
Check in Recovery Mode
- Boot to Recovery (Cmd+R)
- Open Disk Utility
- Can you see your main volume?
- Do NOT run First Aid yet
- Just observe what's visible
When Professional Recovery Is Required
You should seek professional data recovery if any of these apply:
- •Safe Mode doesn't work
- •Recovery Mode can't see the drive properly
- •Data is not backed up
- •This is your work computer
- •You've already tried reinstalling
Our Recovery Process
Turnaround Time
2-5 business days
Success Rate
95% for prohibitory sign Macs
What happens when you bring your drive to us:
- 1Boot from external and assess drive
- 2Image the drive completely
- 3Extract user data files
- 4Verify document and photo integrity
- 5Return data on new media
Frequently Asked Questions
Related Guides
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APFS Volume Unmountable – Data Recovery
Disk Utility shows your APFS volume as unmountable or displays APFS container errors.
External Hard Drive Not Mounting on Mac – Disk Utility
Your external hard drive appears in Disk Utility but won't mount, appearing grayed out.
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