Apple Studio failed to boot beyond login screen.

Question

Apple Studio failed to boot beyond login screen.

My Apple Studio failed to boot beyond the login screen. I entered my password, the progress bar started, stalled, and then the Studio Display went blank. On pressing the wake button, the login screen appeared again, asking for my password. Following searched advice at Apple Support, I disconnected all peripherals and the Studio then booted as normal. When it restarted, the attached crash log appeared.

Can anybody decipher that for me to provide any useful advice?

One other thing that might be worth mentioning is that I have a UPS, and I have wondered recently whether that is causing problems.

Crash log.log

Mac Studio, macOS 26.6

Posted on Oct 3, 2026 6:34 AM

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Answer 1

den.thed

Level 10

98,312 points

Oct 3, 2026 8:22 AM in response to Neville Goodman1

That issue can be caused by external devices and/or third-party software that is set to open at login.

To narrow down external devices, remove them from the Mac one at a time and re-test.

To narrow down third-party software, disable them from opening at login and re-test.

see > Open items automatically when you log in on Mac - Apple Support

Use EtreCheckPro to give us a bigger picture of what is causing your startup issue.

Download and run the free version of EtreCheckPro, from > https://etrecheck.com/en/index.html

Then post back here with your Report, as per > How to use the Add Text Feature When Post… - Apple Community

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Answer 2

kaz-k

Level 9

53,288 points

Oct 3, 2026 10:41 AM in response to Neville Goodman1

Hi,

A watchdog timeout error on macOS occurs when a system monitor (watchdogd) detects that a core hardware driver or software process—such as the System Management Controller (AppleSMC) or WindowServer—has stopped responding, triggering a kernel panic and forcing your Mac to restart.

Try to startup in Safe mode, then normal boot could solve your issue.

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Answer 3

Oct 3, 2026 10:15 AM in response to den.thed

Thanks. I disconnected all my peripherals and the Studio has behaved since then. I'll investigate the peripherals one-by-one and get back to you if the problem recurs.

One thing that EtreCheck found was a couple of uninstalled extensions, and it had this advice:

f the container application is Not found! then the system extension has been incorrectly uninstalled. In this case, there will be no Show in Finder button to locate the app. Instead, use the Uninstall button to open System Settings. Locate the extension under Extensions. It could be listed under Endpoint Security Extensions or Network Extensions. Click on the ⓘ button. Then click on the 𝌀⃝ button and choose Delete extension to remove the extension.

I found the extensions under System Settings, clicked on the i button -- but where is the 3-dot button?

Thanks!

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