Backup: Is it doable to vary the Sparsebundle password of the time machine in sequoia macOS?

I’ve a headless mac mini that has a SMB quantity to which my MacBook Professional is configured to make a time again copy. Each are working the most recent model of Macos Sequoia (15.3.2).

I’m making an attempt to vary the password of my backup copies of the encrypted community time machine and I’m at the moment urgent a wall. Might I do know, this isn’t a documented characteristic for backup copies of community time machines, however since Time Machine makes use of sparsebundles and there’s a usefulness to vary their encryption keys, I suppose Time Machine might bear it.

What I’ve tried to do:

1. Change the sparsebundle encryption password utilizing sudo hdiutil chpass /Volumes/Backups/’s MacBook Professional.sparsebundle
   • I confirmed that I can experience manually ’s MacBook Professional.sparsebundle (Double clicking on it and getting into the brand new password)
2. MANUAL MANUAL MANUAL OF THE TIME MACHINE, FACE WITH A MESSAGE THAT I NEED TO UPDATE MY PASSWORK. So I click on on “Replace password”.
3. Asks me to enter my new password: entry the brand new password and click on Enter
4. After a number of seconds, I see the identical error display: the brand new password is knowledgeable as incorrect (though as talked about, I can open the sparsebundle with the brand new password)

I’ve checked out Syslogs for Backupd and I discovered some that appear attention-grabbing:

2025-03-18 22:54:32.936183+1100 0x9937a    Default     0x77ba5              514    7    backupd: (DiskImages2) (com.apple.DiskImages2:Default) +(DIEncryptionFrontend hasGUIaccess): Consumer session flags: 0x1 (0x1=root, 0x10=graphics, 0x20=hasTTY, 0x1000=IsRemote), secRes=0
2025-03-18 22:54:35.039877+1100 0x9937a    Error       0x77ba5              514    7    backupd: (DiskImages2) (com.apple.DiskImages2:Default) +(DIError errorWithDomain:code:description:verboseInfo:error:): Can't retrieve passphrase from person by way of TTY or GUI (err code 25)
2025-03-18 22:54:35.039967+1100 0x9937a    Default     0x77ba5              514    0    backupd: (libxpc.dylib) (com.apple.xpc:connection) (0x625bd8a00) invalidated as a result of the present course of cancelled the connection by calling xpc_connection_cancel()
2025-03-18 22:54:35.040084+1100 0x9937a    Error       0x77ba5              514    0    backupd: (TimeMachine) (com.apple.TimeMachine:DiskImages) Failed to connect utilizing DiskImages2 to url '/Volumes/.timemachine//ADD2A9B1-B032-4287-B688-2277179038A2/Backups/'s MacBook Professional.sparsebundle', error: Error Area=NSPOSIXErrorDomain Code=25 "Inappropriate ioctl for machine" UserInfo={DIErrorVerboseInfo=Can't retrieve passphrase from person by way of TTY or GUI}
2025-03-18 22:54:36.307690+1100 0x99379    Error       0x77ba5              514    0    backupd: (TimeMachine) (com.apple.TimeMachine:BackupDispatching) Backup failed: BACKUP_FAILED_DISK_IMAGE_WRONG_PASSWORD (53)

From the above evidently DiskImage2 You’ll be able to’t get the brand new password ("Can't retrieve passphrase from person by way of TTY or GUI (err code 25)"). I’m not certain why that is occurring, since I supplied the password when he requested me to replace it. Possibly this isn’t transferred to the diskimage2 course of that’s being executed as root? I’m not certain, but it surely undoubtedly appears that it ought to work because it acknowledges the mandatory password to replace. I additionally tried to remove the outdated password from my login and system keys in entry to the keychain in any file that would discover that it appeared related, nonetheless the identical error.

The one resolution I’ve discovered is to vary the password to the unique (utilizing the identical sudo hdiutil chpass area). After altering the password once more, I can begin a handbook backup and may mount the sparsebundle efficiently. I ponder if which means that Time Machine shops a duplicate of the Sparsebundle password elsewhere.

I’ve additionally learn that Time Machine makes a password truncated (https://apple.stackexchange.com/a/331768/621735). The unique password is saved in my 1Password vault and I can see that entry to the keychain has a truncated model saved (26 characters). I’ve tried passwords <26 characters and I am nonetheless encountering the identical downside, so I do not assume it is associated to this, however I may very well be fallacious.