Downgraded from Monterey to Mojave, very slow system

[flyffof]

Hello,
Recently, I opened a problematic AI file, and my Big Sur OS got very slow. All apps were lagging and unusable. I tried to repair disk in disk utility, reset SMC, reset pram. I tried to restore system to a previous date, but after the restore, the system is still very slow. I thought upgraded to the new OS Monterey could solve the slow problems. But it's even worse, the mac got so low I cannot use it at all. After a long time of researching online, I found out Monterey has a lot of problems since it's pretty new. So I created a bootable usb disk and erased and installed Mojave. The system seems usable, but after the Adobe apps were installed, the system becomes slow and lagging again. Every time at startup, I kept getting the dialog box, Incompatible Disk, this disk uses features that are not supported on this version of Mac OS. I did some more research, found out that Monterey uses a newer firmware compared to Mojave.

So my question is, could the firmware incompatibility causes the system to slow down?
Also, what's the Incompatible Disk dialog box mean? How do I disable it?
How do I fix the slow down? Disk Utility says my disk is fine.

Any feedback would be greatly appreciated, thank you!

 

[conmee]

Even though Mojave, Catalina, Big Sur, and Monterey use APFS, Apple has introduced changes to APFS since Mojave that are incompatible with Mojave (Note: I've only seen this error with internal/primary disks, not sure if Mojave issues same message when accessing external APFS volumes formatted with a newer macOS). You should boot with your Mojave bootable USB and use Disk Utility to erase the disk you want to install Mojave on. You may need to unmount the volumes on the installation disk and then erase the disk. What I do is use Disk Utility from a Mojave bootable USB and erase/format the installation disk as HFS+ to make sure APFS formatting is removed completely and then run Mojave install (Mojave will then convert it to APFS as part of the installation process). This should fix your "Incompatible Disk" error.

I've installed Monterey on my 2019 MacBook Pro and it has the latest firmware/iBridge updates and works fine with Mojave.

 

[conmee]

Also, a friend uses Adobe Creative Cloud products and he was having an issue where his entire drive looked full and would bog down when doing video work. Turns out Adobe After Effects (in his case) was consuming/reserving all the free space and not letting it go. I don't recall the exact preferences (Cache, Scratch, etc) but he said he made some preferences changes so Adobe wouldn't use all available free space and he deleted the huge cache file. After that, things ran smoothly again. Hope that helps.

 

[Honza1]

Upgrading/downgrading system because existing became slow is nuclear option. It seems extreme to me.
Sudden slow down of system is logically issue with software (system & software) or hardware. There are methods to try to identify... But, since you already started with extreme option, easiest is to wipe the disk again and instal plain vanilla system - any one your mac is capable of. Firmware typically supports systems backward for purpose of reinstallation. Personally, I would use current Big Sur or whatever Internet recovery gives you (easiest). Then run clean system for some time and check speed. Try few basic things in Safari and other built in apps. If that works fine, hardware should be fine. Then install what you need. If that breaks it, it is your software which you are installing. There is really no other way to know.
One of my prior system became slow at some point without any apparent reason. After some time my SSD died. Since this was system with soldered SSD, it required mainboard replacement (I had AppleCare, so it was free). Good luck.

 

[flyffof]

Even though Mojave, Catalina, Big Sur, and Monterey use APFS, Apple has introduced changes to APFS since Mojave that are incompatible with Mojave (Note: I've only seen this error with internal/primary disks, not sure if Mojave issues same message when accessing external APFS volumes formatted with a newer macOS). You should boot with your Mojave bootable USB and use Disk Utility to erase the disk you want to install Mojave on. You may need to unmount the volumes on the installation disk and then erase the disk. What I do is use Disk Utility from a Mojave bootable USB and erase/format the installation disk as HFS+ to make sure APFS formatting is removed completely and then run Mojave install (Mojave will then convert it to APFS as part of the installation process). This should fix your "Incompatible Disk" error.

I've installed Monterey on my 2019 MacBook Pro and it has the latest firmware/iBridge updates and works fine with Mojave.

Hello, thank you for the prompt reply. The imac is formatted to APFS. I had used the Mojave bootable USB to start up my imac, and accessed disk utility from there, and erase my imac HD. But it left an "updated" partition, and I don't know how to delete it. After I installed Mojave, I checked the speed of Safari, mail apps. It was a bit sluggish, but manageable. Then I installed Adobe photoshop and illustrator. It became slower. It took a long time to install them.

My biggest concern is finding out the cause of the slow down of the imac, will fixing the "Incompatible Disk" error fix the slow down problem?

 

[flyffof]

Upgrading/downgrading system because existing became slow is nuclear option. It seems extreme to me.
Sudden slow down of system is logically issue with software (system & software) or hardware. There are methods to try to identify... But, since you already started with extreme option, easiest is to wipe the disk again and instal plain vanilla system - any one your mac is capable of. Firmware typically supports systems backward for purpose of reinstallation. Personally, I would use current Big Sur or whatever Internet recovery gives you (easiest). Then run clean system for some time and check speed. Try few basic things in Safari and other built in apps. If that works fine, hardware should be fine. Then install what you need. If that breaks it, it is your software which you are installing. There is really no other way to know.
One of my prior system became slow at some point without any apparent reason. After some time my SSD died. Since this was system with soldered SSD, it required mainboard replacement (I had AppleCare, so it was free). Good luck.

Thank you for the reply. Before I tried to erase and then install the system as new, I tried to reinstall the apps, but the imac was too slow and laggy and unusable, so I had to reinstall the system. Ok. Maybe I can try to reinstall the apps see if it helps, then erase and reinstall the system.

 

[MarkC426]

Provide full specs of your system, i.e. ram, gpu, disk type size etc.
It will help with diagnosis.

 

[conmee]

Boot from your bootable USB and unmount the "Upgrade" volume then try to erase/format it. That is what is causing the "Incompatible Disk" error. I had that volume on my MacBook when I installed Monterey and deleted it when I reinstalled Mojave. Not sure if the volume is permanent or just used by the Monterey installer or for OS updates. Anyhow, you'll need to remove it to eliminate the incompatible error. But it shouldn't have any effect on your iMac performance. If you can't remove it with Disk Utility you'll need to use Terminal and some command lines. But it sounds like your iMac has other issues if it's sluggish with a fresh installation.

 

[KeesMacPro]

I had used the Mojave bootable USB to start up my imac, and accessed disk utility from there, and erase my imac HD. But it left an "updated" partition, and I don't know how to delete it

Booted from the USB Mojave installer, open Disk Utility and go to " view" set it to "show all devices".
You should see the internal drive and it's subdivisions/containers/partitions .
Delete the drive itself and reformat to APFS non case-sensitive.

You now should see the device and a single APFS container where you can install Mojave.
As suggested by @Honza1 , I'd test some apps etc on the clean install and add one by one 3rd party software to be able to find the culprit.
IMO it is very well plausible that Mojave runs much smoother/faster on your Mac than Monterey , especially if your iMac is a bit older (but without the specs it's a guess).

 

[Fishrrman]

"The imac is formatted to APFS. I had used the Mojave bootable USB to start up my imac, and accessed disk utility from there, and erase my imac HD. But it left an "updated" partition, and I don't know how to delete it."

I'm thinking that you didn't erase THE ENTIRE DRIVE.

It's easy for users to make this mistake when using disk utility.

That's because there's a small icon in disk utility on the upper left labeled "view".
To erase the ENTIRE disk, you must go to it first and choose "show all devices".
NOW you can see the physical drive in the "list on the left", and erase it.

Did you do this when you erased the drive prior to installing Mojave?

If you didn't, what you need to do is... well... do it all over again.
That is:
- back up first (of course!)
- boot from the USB flashdrive
- open disk utility
- GO TO THE VIEW MENU and choose "show all devices"
- Select the "top item" on the left that represents the physical drive
- Erase it
- Quit disk utility
- Open the installer and re-install the OS.

NOW the ENTIRE drive has been erased and you'll get a completely "fresh" install.

 

[flyffof]

Provide full specs of your system, i.e. ram, gpu, disk type size etc.
It will help with diagnosis.

The specs are:
iMac (Retina 5k, 27 in, 2019)
Processor 3.7 ghz intel core i5
Memory 32GB
Startup Disk Mac HD
Graphics Radeon Pro 580x 8 GB

 

[DeltaMac]

Do you have a fusion drive? I think it is possible that when you erased the drive, you also may have split up the fusion drive, then reinstalled your system on only the hard drive device (not using the SSD drive at all), which could explain your slowdown -- if the system is running on only the spinning hard drive, it will be quite slow.
I think it would help to see if that has happened. Post a screen shot of your terminal window after running the command

diskutil list

 

[flyffof]

Thank you for everyone's feedback. I think this time I'll format the entire disk (per your instructions), and install the Mojave OS, then try to install the Adobe softwares to see if there's any slow down.

 

[flyffof]

Do you have a fusion drive? I think it is possible that when you erased the drive, you also may have split up the fusion drive, then reinstalled your system on only the hard drive device (not using the SSD drive at all), which could explain your slowdown -- if the system is running on only the spinning hard drive, it will be quite slow.
I think it would help to see if that has happened. Post a screen shot of your terminal window after running the command

diskutil list

Hello Delta Mac, please see attachment.

 

[DeltaMac]

Your fusion drive appears to be OK, at least in that list.

 

[flyffof]

Hello everyone, I tried to erase the entire disk got got this error "Erase Process Has Failed."
I did some research online, but still don't know how to erase it. I don't know why my imac has so many disks.
Please see attachments.

 

[flyffof]

Hello, I realized my imac cannot format the entire disk to APFS. I formatted it to (JHFS+). My imac is 2019, it came with APFS. I heard APFS is faster than (JHFS+). Now I got so many disks. I'm so confused, and don't know what to do now. Please help.

 

[flyffof]

It seems after closing disk utility, and reopened it. The two APPLE disks disappeared. Now my drives looks fine now. I tried to format the disk to APFS again.

 

[flyffof]

So I successfully installed Mojave. I tried to open apps to check the speed. Every app I opened would take a long time to open, and everything I clicked, the cursor would turn into a rainbow and spin. Is something wrong with my Mojave installer, or something wrong with my hard drive? It's already slow at a fresh install, I'm not sure if doing security updates would help. Should I try installing another OS, like Bis Sur?

 

[Honza1]

Something is wrong with your drive setup. Do not bother to update or install anything else, clean macOS should run fast, whichever you install. This is not normal...
These fusion drives are nightmare to troubleshoot this way. My experience with them has been, well, dreadful. I built my own in mini and after some time the fusion drive became extremely slow. I have not found way to revive it to proper speed so I ended up splitting it and using SSD for system and HD for larger data. That worked lot better for long time.
My suggestion is, if you have Apple store nearby, to take it there and ask them for help. US Apple stores will provide help with this for free and will reinstall proper system on this.
My own solution - if it can be done - would be to install larger SSD. Either swap the HD for SSD or replace the original SSD in the iMac. And then run off the SSD itself and not use Fusion drive. Would make life much easier.

 

[TMRJIJ]

So I successfully installed Mojave. I tried to open apps to check the speed. Every app I opened would take a long time to open, and everything I clicked, the cursor would turn into a rainbow and spin. Is something wrong with my Mojave installer, or something wrong with my hard drive?

Probably the quickest way to tell if your Hard Drive is failing to view its general health of it. DriveDx is pretty fast at finding obvious signs of Mechanical HDD failures