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Thunderbolt Problems IMAC 2013 - Cant do any firmware downgrade

Hello! I have this problem too.

Help please!!!!!!!!

Now, Im using Mojave.


"My late 2013 27" iMac is having some Issues with Thunderbolt and it seems that a Firmwareupdate is needed.

While Displays connected to the Thunderbolt Port work fine, it appears that both Ports won't recognize Harddrives at all.


A comparison to my Macbook Pro (early 2015) where everything works perfectly showed a difference in the TB-Firmware:

Thunderbolt-Firmware Version on the iMac: 23,10

Thunderbolt-Firmware Version on the Macbook Pro: 27,10

Booth Devices are running macOS Sierra 10.12.3


I figured the Thunderbolt FM Update v1.2 might fix the Issue, however it's not appearing as an Update in the AppStore, and none of the offered Downloads on the Apple Website will currently work.

Every 1.2 Update Installer states that the Software is not supported by my System, and will not continue to run the Update.


Any Ideas and Suggestions on how to get the Update running without a complete OS reinstall are highly appreciated."


iMac 21.5", macOS 10.14

Posted on May 16, 2019 3:04 PM

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Posted on May 16, 2019 3:54 PM

The following are the only firmware updates for 2013 iMacs.



If you keep your macOS system current, then any needed firmware updates will be installed when you upgrade macOS. This is all done automatically. In your case, you may find you have a cable problem. Although DisplayPort cables and disk drive cables look alike with Thunderbolt 2.0, they are different. The latter will work as the former, but not vice-versa.

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Question marked as Best reply

May 16, 2019 3:54 PM in response to IsraelCurtas

The following are the only firmware updates for 2013 iMacs.



If you keep your macOS system current, then any needed firmware updates will be installed when you upgrade macOS. This is all done automatically. In your case, you may find you have a cable problem. Although DisplayPort cables and disk drive cables look alike with Thunderbolt 2.0, they are different. The latter will work as the former, but not vice-versa.

May 16, 2019 4:18 PM in response to Kappy

Hello and thanks for the reply!
The sound card and my external disk Lacie are connected by lightning. Since I did an upgrade to Mojave, like the ports that went off the stage to upgrade thunderbolt firmware. I've tried other macs with the same cables and everything works fine. Not mine does not work. I just turned on the monitor, but it's display port. I already tried to downgrade with Yosemite and Maveriks but nothing. :(











May 17, 2019 1:44 PM in response to IsraelCurtas

I havd no solution for you. It sounds like a hardware issue with the computer since, as you say, the peripherals all work on other computers. Just not yours. You cannot downgrade the firmware. You can only downgrade macOS.


macOS Reversion- How to Downgrade from Mojave


BTW: when you post here, you can enter your text directly in the message editor. You do not need to use the Code Insertion tool except to enter actual code.

Thunderbolt Problems IMAC 2013 - Cant do any firmware downgrade

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