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Today I wanted to open my .dmg files and I could not open any of them on the old iMac computer, but I can open them on the new computer - strange. I have all the passwords as they are in Apple key Chain - but none of them I can open on the old computer - how is that ???
[Re-Titled by Moderator]
iMac 24″, macOS 15.1
Are you booted into your old Mac or accessing it from your new Mac over a LAN?
What happens when you try?
What Mac model and year are you two Macs and what systems are they running?
Did you create the dmgs or were they from another source?
I created the .dmg s using Disk Utility . Strange also that on the new Mac there are only AES 128 encrypting ,on the Old Mac I can still use AES 256 encryption .I have a mobile internet ,which I deem it most bad ewer 5G mobile internet ,I have a router of course ,it is a mobile router. Big companies has this mobile internet - and in this house there are no FIBRE internet - which is indeed most strange too .
I can open all the .dmg files on my new Mac ,but not on the old one . Also the old Mac has a better passwords Generator and it generates short passwords which I deem somewhat risky . - a lots of things is strange .
In Finder double clicking on the file - then it says : The disc image could not be opened.Could not load file or wrong format on UDIF - image .
Klicking on the Desktop ,it says that ,Disc image cannot be opened as Original is not found , as I remember.
My first thought was that you used APFS as the filesystem for the .DMG … and that the older Mac was running a version of macOS that predated APFS – i.e., one that predated High Sierra. That would easily explain it.
But then you said that the newer Mac is running Sonoma and that the older one is running Monterey.
How are you accessing the DMG file on the older Mac? Are you transferring it using a USB stick or drive? If so, then maybe the file is being corrupted on the USB stick (very common). See if you can transfer that file from the old Mac back to the new Mac to see if the new Mac can open the DMG file after being transferred back & forth.
If you are downloading the file from the cloud service, then I have seen issues trying to access archive files once downloaded from the cloud.
Was the DMG file created on the newer Mac?
The new Mac can open the .dmg files . The old Mac uses Mac OS extended journal ,on the new MAC I also created a .dmg file but that also uses Mac OS extended journal , that APF I newer heart about ,it is a new something? I can open all the .dmg files on the new Mac ,but not on the old one, but maybe it does not matter so much ?
garage4996 wrote:
The new Mac can open the .dmg files . The old Mac uses Mac OS extended journal ,on the new MAC I also created a .dmg file but that also uses Mac OS extended journal , that APF I newer heart about ,it is a new something? I can open all the .dmg files on the new Mac ,but not on the old one, but maybe it does not matter so much ?
APFS is a new filesystem that Apple introduced with High Sierra. It has features which make it especially suitable for use on SSDs. Macs running recent versions of macOS use APFS on their internal SSDs – and would likely also offer APFS as the default format for creating a new disk image.
Macs running operating systems that predate APFS cannot mount APFS-formatted drives or APFS-formatted disk images (.DMGs). If you are creating a .DMG and you need it to be readable on an older Mac, you must select one of the filesystems that an older Mac can read – like HFS+ / Mac OS Extended.
The Old Mac is Monterey ,the new one is Sonoma .
Unable to open .DMG files on old iMac
