Can't reset PRAM/NVRAM on 2018 Mac mini.

Doc69

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Original poster
Dec 21, 2005
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I recently bought a 2018 Mac mini. However, I don't seem able to reset PRAM/NVRAM like on all my other Macs, i.e. by holding down the CMD+Option+P+R keys on startup. The 2018 Mac mini just boots normally even though those keys are held down. Is anyone else with a 2018 Mac mini able to get into the PRAM/NVRAM loop, like on older Macs? I just want to rule out that there is something wrong with it. Or perhaps Apple changed something with this Mac? I've noticed that there has been some other changes to Macs that have the T2 security chip, so perhaps this is related? Thanks!
 

DeltaMac

macrumors G3
Jul 30, 2003
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Delaware
Do you have a firmware password set on your 2018 Mac mini?
If you are not sure about that, try booting to your recovery system (boot while holding Command + R). You will get a password window (with a padlock graphic) before you can get to the recovery system. Enter your firmware password, then, from the menus, choose the Startup Security Utility, then click Turn Off Firmware Password. Then, you will be able to reboot and reset the NVRAM. Turn your firmware password back on when you are done.
 

Doc69

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Original poster
Dec 21, 2005
498
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Do you have a firmware password set on your 2018 Mac mini?
No. But I set one up as soon as I got the Mac mini. But then I was not able to turn it off. It took a lot of troubleshooting to finally figure out that I had to boot into recovery mode from an external USB flash drive with the Mojave installer to get into the Startup Security Utility and disable the firmware password. When I booted from the regular internet recovery, it did not work. But when I finally was able to turn it off, I left it off.

Another issue I have with this Mac mini (running Mojave), that started after I installed Catalina on an external drive, is that I can no longer boot into the regular recovery partition (CMD+R) without the external Catalina drive attached. Otherwise it goes straight into internet recovery and ends with a -1008F error. I have called Apple and they have not been able to help so far but have promised to get back to me. It may have something to do with the T2 chip firmware. Once you install Catalina it updates it. And Catalina apparently no longer supports booting from an internal recover partition.

If someone could confirm if they are able to reset PRAM/NVRAM on their 2018 Mac mini or not, using the normal CMD+Option+P+R key command on startup, that would be great.
 

IngerMan

macrumors 65816
Feb 21, 2011
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Michigan
If someone could confirm if they are able to reset PRAM/NVRAM on their 2018 Mac mini or not, using the normal CMD+Option+P+R key command on startup, that would be great.

I can confirm it does not keep rebooting while holding the 4 keys. It is just going to login screen. I tried it a few times having only the keyboard, mouse and HDMI to the screen. I removed my eGPU and external hard drives and web cam.

It may have something to do with running Catalina 15.3

I swear I did this a few times running Mojave.
 

Doc69

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Original poster
Dec 21, 2005
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I can confirm it does not keep rebooting while holding the 4 keys.
Thank you for testing that. Then your mini does the same as mine. It would be interesting to hear from a couple of other owners too in order to know for sure if this is normal or not, and if the behavior changes when upgrading from Mojave to Catalina. I'm on Mojave but was perviously on Catalina. And I read that the firmware in the T2 chip updates when you upgrade to Catalina, so if you go back to Mojave, the new firmware stays. So if the behavior changes with Catalina, this could we why I also have that behavior, even though I'm on Mojave?

The document that Fishrrman linked to was great, but did not shed any new light on this issue. But in the Apple document below, they outline a new procedure to reset NVRAM or PRAM. They no longer mention the chime sound (gone on newer Macs), and it seems like the reset should happen during what seems like a normal boot.

So I changed some sound volume and display resolution parameters and followed the instructions. After the reboot, none of the parameters had been reset, so I see no evidence of a successful reset. The only thing I noticed was that, after setting the display resolution to 1280x720, if I boot without golding down any keys, the resolution of the login screen is 1280x720, as expected. However, if I hold down the ⌘+⌥+P+R keys, the resolution of the login screen goes back to 1920x1080, the native resolution. But once I log in, it's 1280x720 again (and on subsequent normal reboots), so nothing was reset, AFAICT.

It would be great of more people shared their experiences here so we can figure out what is normal behavior for the 2018 Mac mini. I have talked to two senior Apple advisors, and they just gave me the regular classic instructions, which obviously did not work at all.
 
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Doc69

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Dec 21, 2005
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I can confirm it does not keep rebooting while holding the 4 keys.
Hi IngerMan, since the Apple stores are closed, if you have the time, I would appreciate if you (or anyone else with a 2018 Mac mini) could do the following quick test for me:
Change the input and output sound volume to something like 10-20%, change the display resolution to something much lower than your native resolution, change the startup disk, if possible and change the time zone. Then shut down and hold down the ⌘+⌥+P+R keys after you restart the mini. When you get back up, please let me know if the new settings are still there or if they have been reset to default.

On all my other older Macs, these settings will go back to default after I reset NVRAM. But not on my 2018 mini. Knowing if your mini behaves in the same way will help me determine if there is something wrong with mine. Since I have learned that new Macs with T2 chips no longer do the boot loop when resetting NVRAM, it's also quite possible that Apple now also store many of the settings in memory somewhere, in order keep them from resetting even if you do a successful NVRAM reset. If so, that would be great, actually. Thanks.
 

frou

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Mar 14, 2009
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If you are familiar with using Terminal, check out the "nvram" command as a possible alternative to the four finger keyboard salute.

Screenshot 2020-03-28 at 08.29.06.png
 
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IngerMan

macrumors 65816
Feb 21, 2011
1,351
313
Michigan
Hi IngerMan, since the Apple stores are closed, if you have the time, I would appreciate if you (or anyone else with a 2018 Mac mini) could do the following quick test for me:
Change the input and output sound volume to something like 10-20%, change the display resolution to something much lower than your native resolution, change the startup disk, if possible and change the time zone. Then shut down and hold down the ⌘+⌥+P+R keys after you restart the mini. When you get back up, please let me know if the new settings are still there or if they have been reset to default.

Hi Doc69, sorry I did not see this for a few days. But I can confirm I just set the volume input/output to 10%, resolution to the lowest setting, start up disk to my external CCC, time zone to one to the west of me. Powered down: power up with my wireless KB plugged in while holding the Option + Command + P + R.

Results = I thought it was working for it was taking longer than usual but that's because it was powering up on the external start up disk lol..... All settings stayed and I had to set them back to my preference.

So my machine acts the same as yours.

Hope that helps.
 

Doc69

macrumors 6502
Original poster
Dec 21, 2005
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So my machine acts the same as yours. Hope that helps.
Hi IngerMan, thank you very much for doing the test. It helped a lot. I also had a friend do it and the result was the same for him as well (Catalina). So I think we can now safely assume that everything is working properly and that Apple has changed the NVRAM reset behavior drastically on Macs with T2 chips. Not only is the boot loop sequence and chime gone, as per their updated Apple instructions in my previous post, but now display resolution, sound volume, startup disk and time zone are not reset as they were before as well. Strange that there is no information about this on Apple's website, nor does any of the senior advisors I've talked to know about it either. I'm glad we were able to figure this out for ourselves. 😀 If anyone has additional information on this topic, I would greatly appreciate it.
 
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Doc69

macrumors 6502
Original poster
Dec 21, 2005
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If you are familiar with using Terminal, check out the "nvram" command as a possible alternative to the four finger keyboard salute.
Thank you for this. I use Terminal frequently, but my knowledge is not extensive enough that I could deduce from your document what string to enter to clear the NVRAM in the same way that ⌘+⌥+P+R does. Do you know? Also, it seems like a clean restart is necessary anyway. But obviously it would be good to know an alternative to the old ⌘+⌥+P+R. 😀
 

frou

macrumors 6502a
Mar 14, 2009
728
787
Go with "sudo nvram -c" then Restart.

Beforehand you could do "nvram -x -p >~/Desktop/a.txt", then after the Restart do "nvram -x -p >~/Desktop/b.txt", to get two text files on your desktop that can be compared to see what difference it made. (Presumably the "after" file won't be completely empty because just the act of fresh booting the OS probably writes some things to NVRAM).
 
Last edited:

Doc69

macrumors 6502
Original poster
Dec 21, 2005
498
36
Beforehand you could do "nvram -x -p >~/Desktop/a.txt", then after the Restart do "nvram -x -p >~/Desktop/b.txt", to get two text files on your desktop that can be compared to see what difference it made. (Presumably the "after" file won't be completely empty because just the act of fresh booting the OS probably writes some things to NVRAM).
Thanks, I'll definitely try that. I also assume that this trick could be used to actually see if ⌘+⌥+P+R actually did something or not?
 

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