iMac stuck in reboot loop after failed macOS 26 upgrade

Do you have any of the following types of third party apps installed:

• Antivirus
• Cleaning
• Security
• VPN
• Maintenance

then that likely is the cause. If the answer is no call AppleCare asap

Also, what model year iMac??????

Nicollivier wrote:

Hi Everyone,

I’ve downloaded the latest version of macOS 26 on the 15th.

After rebooting the computer was blocked at the beginning of reboot process (small white line showing progress, but in this case no progress at all).

After a while I had to force the reboot which is maybe my mistake…

Now I cannot access to the restore mode, it continues to reboot every 2 or 3 seconds

Any possible to save my iMac?

Thx

Nicolas

[Re-Titled by Moderator]

Original Title: Upgraded failed, iMac bricked?

Boot into Recovery and reinstall the macOS...?

How to reinstall macOS

Recovery (both M1/M2/M3/M4 and Intel) — How to reinstall macOS - Apple Support

Still have an issue—

Call Customer Support (800) MY–APPLE (800–692–7753)

or on line https://getsupport.apple.com/

or call AppleCare Support at 1-800-APLCARE (800-275-2273)

Outside the USA—Contact Apple for support and service by phone

See a list of Apple phone numbers around the world.

Contact Apple Support - Apple Support

You have Recovery, ALL Macs do. Please follow the instructions in the link provided by Leroy.