iMac shows folder with question mark after security change

Question

iMac shows folder with question mark after security change

Hello all,

I just dug out my first Imac and am now trying to get her running once more. Last time I put the Imac into recovery mode as I wanted to boot up Big Sur from a flash drive. When trying to boot up I got a denied circle and the Imac turn off.

Then I tried in recovery mode t change the security settings to medium by inputting a password. Now all I get in a folder with question mark. Not possible to get into any mode right now.......

I am using a windows keyboard and I guess the Imac is from 2006. (no lables on the machine itself)

You guys have any ideas???

Thanks

RN

Posted on Dec 1, 2025 7:38 AM

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Answer 1

Ingo2711

Level 10

80,019 points

Dec 1, 2025 7:58 AM in response to ringthosebells

Did you already have a look at this related article?

If your Mac starts up to a question mark - Apple Support

If other start up screens pop up, have a look at this article:

If your Mac doesn't start up all the way - Apple Support

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Answer 2

John Galt

Level 10

155,042 points

Dec 2, 2025 4:16 PM in response to ringthosebells

Identify your iMac model - Apple Support doesn't go back as early as 2006 but that era puts it in the category of the first ones that had the appearance of a thick display on a stand. Look underneath that support stand for a serial number or other identifying markings (don't post serial numbers here).

Big Sur or anything anywhere near it won't work. You will absolutely positively need the original, grey, System Install DVD that must accompany those Macs from cradle to grave. If it was built prior to 2006 not even Snow Leopard will work.

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Answer 3

Dec 2, 2025 11:25 PM in response to John Galt

Thanks for all the information, yes my Mac is the "Thick screen" and super old. Unfortunately the startup DVD is long gone. Pity, the computer itself used to run super :-).

Anyway, thanks again to all.

RN

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Answer 4

HWTech

Level 9

68,408 points

Dec 1, 2025 9:21 AM in response to ringthosebells

You need to identify the exact model of that iMac in order to know what versions of macOS are compatible with it and whether you have Internet Recovery Mode as an option. You can get the exact model by entering the system serial number on the Apple check coverage page here, but please don't post the serial number on this forum since it is considered personal information:

View Coverage - AppleCare & Warranty

FYI, Big Sur is only compatible with 2014-2021 iMacs. A 2006 iMac can only run up to 10.7 Lion so you would need to use an OS X 10.6.x Snow Leopard upgrade DVD to install macOS onto a 2006 iMac (same for a few later models as well through 2009).

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