Unable to reinstall Mac OS An unexpected error occurred while signing in. The server gave an error during download: 403 Forbidden.

I’ve used disk utility to delete HD, but I unable to login to iCloud account to reinstall Mac OS.

I get the following error message:


An unexpected error occurred while signing in.


The server gave an error during download: 403 Forbidden.


please advise. Thanks.

iMac, OS X 10.11

Posted on Sep 13, 2025 11:05 AM

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Question marked as Top-ranking reply

Posted on Sep 13, 2025 7:33 PM

Try booting into recovery mode using Command + Option + R. This should either bypass any need to authenticate with the App Store to verify a previous purchase of an older OS, or it will boot to the online installer if the Mac is capable of Internet Recovery Mode.


What is the exact model of your Mac? You can get this information by entering the system serial number on the Apple check coverage page here (please don't post the serial number on the forum since it is considered personal information):

View Coverage - AppleCare & Warranty


1 reply
Question marked as Top-ranking reply

Sep 13, 2025 7:33 PM in response to Charlie_M

Try booting into recovery mode using Command + Option + R. This should either bypass any need to authenticate with the App Store to verify a previous purchase of an older OS, or it will boot to the online installer if the Mac is capable of Internet Recovery Mode.


What is the exact model of your Mac? You can get this information by entering the system serial number on the Apple check coverage page here (please don't post the serial number on the forum since it is considered personal information):

View Coverage - AppleCare & Warranty


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Unable to reinstall Mac OS An unexpected error occurred while signing in. The server gave an error during download: 403 Forbidden.

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