iMac 2019 Start Up Progress Bar Stuck

[TartanTrumpet]

My progress bar sticks at about 50%. I've tried the following:

• Safe mode, it still sticks at about 50%.
• Disk Utility did not report any errors.
• I've reset NVRAM/PRAM, no joy.
• I've reset SMC, no joy.

Extra info:

• This happened today when trying to restart after switching between accounts. I had to restart as when I returned to the account I usually use I suddenly had an issue where applications (Word, Excel, Teams) were crashing as soon as they opened.
• Lately, sometimes the iMac has not been shutting down properly; I've needed to press the power button to shut it down.
• Recently, any start up time has been really slow; possibly taking up 5 mins to restart.

Any insight appreciated.

 

[Juicy Box]

You can try Apple’s built-in HW diagnostic test, see what comes up.

Do you have a Fusion Drive?

 

[TartanTrumpet]

Hi

No Fusion Drive.

HW diagnostic test reported No Issues Found with a Reference Code ADP000.

Thanks

 

[bzgnyc2]

Hi

No Fusion Drive.

HW diagnostic test reported No Issues Found with a Reference Code ADP000.

Thanks

Can you boot up a USB installer disk? Not that you would want to go through with a reinstall but just to know how far that would get.

Also what version of macOS?

 

[Fishrrman]

Boot to internet recovery:
From a "powered off" state, hold down the command+option+R keys.
KEEP HOLDING THEM DOWN AND DON'T LET GO.
Press and release the power on button.
KEEP HOLDING DOWN THOSE KEYS.

If you're connecting to the net using wifi, let go when you're asked for your wifi password.
Otherwise, let go when you see "the spinning globe".

The internet utilities take a while to load, be patient.

When you get to the utilities screen, open the OS installer.

You can now install a fresh copy of the OS to the drive if you wish.
I recommend you accept whatever version of the OS you are offered.

The Mac will reboot one or more times during the install.
The screen will "go dark" for a minute or more with no other indication of activity.
Be patient.

What SIZE is the iMac? 27" or 21" ?
What KIND of drive is inside? If not fusion, is it an SSD, or is it a platter-based hard drive?

 

[Nguyen Duc Hieu]

My progress bar sticks at about 50%. I've tried the following:

• Safe mode, it still sticks at about 50%.
• Disk Utility did not report any errors.
• I've reset NVRAM/PRAM, no joy.
• I've reset SMC, no joy.

Extra info:

• This happened today when trying to restart after switching between accounts. I had to restart as when I returned to the account I usually use I suddenly had an issue where applications (Word, Excel, Teams) were crashing as soon as they opened.
• Lately, sometimes the iMac has not been shutting down properly; I've needed to press the power button to shut it down.
• Recently, any start up time has been really slow; possibly taking up 5 mins to restart.

Any insight appreciated.

My wild guess: Your internal disks are full.

 

[TartanTrumpet]

I kept those command+option+R keys well and truly pressed for a good 10 minutes, but the start up bar still sticks at 50%.

Next, I did a reinstall; however, the problem persists.

It's a 21" iMac from 2019 with a platter-based hard drive.

 

[bzgnyc2]

I kept those command+option+R keys well and truly pressed for a good 10 minutes, but the start up bar still sticks at 50%.

Next, I did a reinstall; however, the problem persists.

It's a 21" iMac from 2019 with a platter-based hard drive.

I take it you can boot up Mac from a installer and get all the way through installation but it fails once it shifts to booting the new installation from the hard drive?

If so, it seems likely your internal hard drive is failing. Not completely but having failed read or writes. Maybe just corruption of key sectors of data but hard to tell without more diagnostics. Did you erase the internal drive before you started the install or did you install over an existing installation?

Assuming a failing internal drive, I would either a) switch to an external NVMe drive in an Thunderbolt enclosure as your boot drive and don't use the internal drive at all (ideally not mounted at all) or b) install a new NVMe drive internally. The latter is cleaner but requires dismantling your Mac, which if you aren't into would likely be better handled by an good service technician. WD SN850X is a good mainstream option for the NVMe SSD that many have reported good success with. I believe an adapter is required for installation of an NVMe drives in that model of iMac as well.

If you want to try to confirm the hard drive is actually failing, and again already assuming the USB installer worked and went all the way through without getting stuck, you could try a secure erase the entire disk (1 pass should be eough). You may have to go View->Show All Devices to see the entire drive to get this option. Also critically this assumes no files/data on the internal disk you want to try to recover. If the installer's Disk Utility generates an error trying to do this or takes an excessively long time, it's likely the hard drive is faliing. Excess is relative to the size of the drive drive but the system should be able to average at least 100MB/second across an HDD (so a 500GB hard drive likely will take 1-2 hours).

On the other hand if it does get all the way through and creates a file system, etc, try to run the installer on it again.

P.S.Since recent versions macOS require APFS for the boot drive and APFS is not a good fit for HDD, switching to an SSD solution for your boot drive as above is still recommended even if you get the HDD working again.