I built a Time Machine server, paleophile.local, out of a 2009 white Unibody MacBook running Sierra on which I installed macOS Server. I attached a 5 TB external via USB to store the encrypted sparse bundles.
It is working splendidly for my early-2015 MacBook Pro running Sierra. Unfortunately I cannot seem to get my girlfriend’s mid-2009 MacBook Pro running El Capitan to backup to paleophile. (Her computer cannot be upgraded to Sierra.)
Our LAN is handled by an Apple Airport Extreme (the flat one) to which paleophile is connected by ethernet. Both my laptop and hers generally connect to the network via WiFi. I have also tested her backup setup over ethernet with WiFi turned off; unfortunately with the same results.
I have setup one account on the server for each of our laptops. Thus her's connects to the server through a different account than mine. Please note that those accounts were setup at the same time and in the same manner so I would expect that they would be identical in configuration. The motivation for these separate accounts was to take advantage of the capacity to apply a disk usage ceiling, particularly on myself.
The error message my girlfriend’s computer reports is that the username and password are incorrect.
Of course I have checked them. To be precise I mounted the server, logging in as the same user with the same password and then mounting the already existing encrypted backup with the key. That all worked perfectly.
Another difference between her laptop and mine that may be relevant is that if I look in 'Keychain Access' for keys related to paleophile I see the following… on my laptop:
paleophile._smb._tcp.local. Time Machine Password
while on hers the quite distinct key appears
paleophile._afpovertcp._tcp.local. Time Machine Password
So it appears that our two machines are attempting to use different protocols to communicate with the server. Is this because my laptop is running Sierra and hers is running El Capitan?
Using the information provided by correspondents in the comments below I examined the configuration of the my Time Machine server. It is setup to accept both AFP and SMB connections for my girlfriend's account. Here is a screenshot of that config panel.
It appears that the TM server is at least configured to accept AFP connections, even if it is failing to do so.
The error message that appears in her Console.app when I try to trigger a backup is
6/6/17 7:33:39.244 PM Finder[239] _CSBackupServerProxyCopyMountPointForDestination returned result code: 29
I've done my best to Google error code 29, but have been unable to find any useful information. What steps should I take to diagnose this problem further?
Here's a sample of the error log on her laptop starting from the moment I select "Back Up Now".
6/6/17 7:33:39.244 PM Finder[239] _CSBackupServerProxyCopyMountPointForDestination returned result code: 29
6/6/17 7:33:41.823 PM lsd[227] LaunchServices: Could not store lsd-identifiers file at /private/var/db/lsd/com.apple.lsdschemes.plist
6/6/17 7:34:02.742 PM lsd[227] LaunchServices: Could not store lsd-identifiers file at /private/var/db/lsd/com.apple.lsdschemes.plist
6/6/17 7:34:02.849 PM lsd[227] LaunchServices: Could not store lsd-identifiers file at /private/var/db/lsd/com.apple.lsdschemes.plist
6/6/17 7:34:12.160 PM lsd[227] LaunchServices: Could not store lsd-identifiers file at /private/var/db/lsd/com.apple.lsdschemes.plist
6/6/17 7:44:48.617 PM accountsd[268] AIDA Notification plugin running
6/6/17 7:44:50.149 PM com.apple.AddressBook.InternetAccountsBridge[375] Checking iCDP status for DSID 126881918 (checkWithServer=0)
6/6/17 7:44:50.225 PM com.apple.AddressBook.InternetAccountsBridge[375] XPC Error while checking if iCDP is enabled for DSID 126881918: Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service named com.apple.cdp.daemon was invalidated." UserInfo={NSDebugDescription=The connection to service named com.apple.cdp.daemon was invalidated.}
6/6/17 7:44:50.225 PM com.apple.AddressBook.InternetAccountsBridge[375] Daemon connection invalidated!
6/6/17 7:45:00.172 PM com.apple.AddressBook.ContactsAccountsService[273] [Accounts] Current connection, <NSXPCConnection: 0x7ff6dad0d680> connection from pid 252, doesn't have account access.
6/6/17 7:45:00.172 PM sharingd[252] [Accounts] Failed to update account with identifier B851945A-3D25-4379-8AD5-AE2A53F59E57, error: Error Domain=ABAddressBookErrorDomain Code=1002 "(null)"
6/6/17 7:45:00.200 PM com.apple.AddressBook.ContactsAccountsService[273] [Accounts] Current connection, <NSXPCConnection: 0x7ff6dad2a7a0> connection from pid 396, doesn't have account access.
6/6/17 7:45:00.200 PM DataDetectorsDynamicData[396] [Accounts] Failed to update account with identifier B851945A-3D25-4379-8AD5-AE2A53F59E57, error: Error Domain=ABAddressBookErrorDomain Code=1002 "(null)"
6/6/17 7:45:00.397 PM com.apple.AddressBook.ContactsAccountsService[273] [Accounts] Current connection, <NSXPCConnection: 0x7ff6dad2e100> connection from pid 274, doesn't have account access.
6/6/17 7:45:00.398 PM CalNCService[274] [Accounts] Failed to update account with identifier B851945A-3D25-4379-8AD5-AE2A53F59E57, error: Error Domain=ABAddressBookErrorDomain Code=1002 "(null)"
6/6/17 8:00:45.025 PM com.apple.prefs.backup.remoteservice[1172] Error in CoreDragRemoveTrackingHandler: -1856
6/6/17 8:00:45.025 PM com.apple.prefs.backup.remoteservice[1172] Error in CoreDragRemoveReceiveHandler: -1856
6/6/17 8:00:50.971 PM sharingd[252] 20:00:50.970 : SDConnectionManager:: XPC connection invalidated
6/6/17 8:01:15.102 PM Finder[239] _CSBackupServerProxyCopyMountPointForDestination returned result code: 29
6/6/17 8:12:34.938 PM com.apple.prefs.backup.remoteservice[1172] Could not connect action, target class TMOptionsSheetController does not respond to -warnCullingPressed:
6/6/17 8:12:34.938 PM com.apple.prefs.backup.remoteservice[1172] Could not connect action, target class TMOptionsSheetController does not respond to -backUpOnBatteryPowerPressed:
6/6/17 8:12:43.377 PM com.apple.prefs.backup.remoteservice[1172] Error in CoreDragRemoveTrackingHandler: -1856
6/6/17 8:12:43.378 PM com.apple.prefs.backup.remoteservice[1172] Error in CoreDragRemoveReceiveHandler: -1856
6/6/17 8:12:51.594 PM com.apple.prefs.backup.remoteservice[1172] Error in CoreDragRemoveTrackingHandler: -1856
6/6/17 8:12:51.594 PM com.apple.prefs.backup.remoteservice[1172] Error in CoreDragRemoveReceiveHandler: -1856
6/6/17 8:13:01.354 PM com.apple.prefs.backup.remoteservice[1172] Error in CoreDragRemoveTrackingHandler: -1856
6/6/17 8:13:01.354 PM com.apple.prefs.backup.remoteservice[1172] Error in CoreDragRemoveReceiveHandler: -1856
6/6/17 8:15:12.530 PM Finder[239] _CSBackupServerProxyCopyMountPointForDestination returned result code: 29
6/6/17 8:16:30.156 PM Finder[239] _CSBackupServerProxyCopyMountPointForDestination returned result code: 29
Best Answer
It turns out the whole AFP vs. SMB question was a red herring. The issue was that her sparse bundle was corrupted.
I deleted her account and her sparse bundle (I now believe deleting her account was excessive) and started her over from scratch with a fresh account and sparse bundle. That solved the problem.
This solution was discovered when a Mac Guru friend of mine suggested that I try backing her computer up to the server by letting her computer use my computer's credentials. Her computer immediately began backing up successfully. That was a big clue as to what was wrong.