Mac Pro macOS Sequoia will not boot with external Thunderbolt/USB devices attached

Boot issue appears to be fixed in macOS 15.3 (24D60)

Bit the bullet and took the risk of updating my Mac pro 2019 to 15.3 (24D60), and it now starts with the Thunderbolt drive attached.

Took about 25 mins and restarted itself about 4 times.

Tight lines out there if you venture forth.

Reset the Startup Disk and test.

see > Change your Mac startup disk - Apple Support

Blow out the Login Items and test.

see > Remove login items to resolve startup problems on your Mac - Apple Support

Repair and/or reinstall the macOS and test.

see > If your Mac starts up to a circle with a line through it - Apple Support

RoaringRatFilms wrote:

Yesterday afternoon I upgraded to MacOS Sequoia 15.3 on my 2019 Mac Pro (12 processor/96GB RAM/1TB Internal SSD/8TB Internal m.2 OWC card) and the update completed with no drama rebooting fine with these externals attached and turned on:

That is good news, thank for the update.

So far so good. I'll report back if I have any issues.

👍

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I have the same problem - two studio displays, one of them is daisy chained to my Mac through a thunderbolt external drive. I wasn't able to restart, stuck on the login screen after providing my password.

I connected my second studio display via thunderbolt directly to my Mac Pro and turned off the externall thunderbolt drive - so, no daisy chaining. It restarts but then again after a while, my computer says a problem occurred and restarts itself.

This is still on-goign and ı am not the only on going through this, right?

I reported this issue to apple just before Christmas. They have taken some logs from my machine and are investigating.This is filed under Case ID: 10*****843. Hopefully, that might help them connect dots if of use to anyone, to give them those case details. Having this separate post title also means they will see it apparently. According to the support guy.

[Edited by Moderator]

FB16100773 (publicly available info)

Thanks so much for this info.

I've scanned through the previous thread.

Have others seen this issue on Macbook Pro 2020 and later?

Did you succeed with 15.3?

nervous to try it as lost so much time with the original upgrade.