Time Capsule backing up one computer but not the other

Welcome to the wonderfully strange new world of High Sierra ... a world of pain mostly to people trying to do Time Machine (TM) backups to network targets like Time Capsule (TC).

Your situation is not unusual.. in fact I have to say typical.

Your setup is unsupported.. ie Apple insist you use the computer directly to the TC by ethernet or wireless.. not via another router like your C7.

Do you have any anti-virus, extra security or accidentally any software that could be classified adware.. anything with up, keep fix etc in the name? Get rid of them all.

At Sierra apple greatly increased security to network drives.. and any other software will unbalance the cart.

Since your MBP2 can see the TC.. open it Finder but not have TM work.. my first recommendation is to reset TM.

How to reset Time Machine.

Apple made no provision to do this.. so you need to get down and dirty.

Delete TimeMachine.plist

Macintosh HD > Library > Preferences > "com.apple.TimeMachine.plist"(delete this file or rename it)

In Finder locate the main Library and Preferences. (you might need to turn on view hidden files).

I renamed the existing file old.. and reboot the computer.. when you start Time Machine again via preferences it will recreate the plist.

I selected the same disk with current backup for the TM backup..

TM counted down 120sec to start a backup.. and then mounts and checks the disk.

You will see TM now goes into a very long period of preparing the backup.. what has happened is that TM discovered the existing backup.

The log shows why.. it is doing a deep scan.

Starting manual backup

Attempting to soft mount network destination URL: afp://ray-local@RT-AC3200-82F0._afpovertcp._tcp.local./Backups.backupdb

Mounted network destination at mount point: /Volumes/Backups.backupdb using URL: afp://ray-local@RT-AC3200-82F0._afpovertcp._tcp.local./Backups.backupdb

Checking for runtime corruption on /dev/disk2s2

Disk image /Volumes/Backups.backupdb/z87proimac.sparsebundle mounted at: /Volumes/Time Machine Backups

Network destination already mounted at: /Volumes/Backups.backupdb

Disk image already attached: /Volumes/Backups.backupdb/z87proimac.sparsebundle, DIHLDiskImageAttach returned: 35 (Resource temporarily unavailable)

Disk image /Volumes/Backups.backupdb/z87proimac.sparsebundle mounted at: /Volumes/Time Machine Backups

Backing up to /dev/disk3s2: /Volumes/Time Machine Backups/Backups.backupdb

Forcing deep traversal on source: "asusz87pro" (device: /dev/disk0s2 mount: '/' fsUUID: 2BB3E4A1-CE4C-350F-B8E8-E69BB22A5DE1 eventDBUUID: 1A326CD6-8C1A-467B-9FB1-3A628959CEFA)

Deep event scan at path:/ reason:must scan subdirs|require scan|

Running event scan

initial consistency scan for '/'

Depending on the size of the backup and speed of the network connection. (if it is network target..) it can take a long time..

It took 20min to complete check of 120GB boot drive backup on fast network.. multiple your disk size by the time. Divide by whatever fraction your network speed is less than 1Gbps. For wireless divide by another 0.5 to include reality over hype. (Maybe 0.1)

Assuming the scan comes up Apples.. (used to mean all good A+)..

The backup will proceed to do a simple incremental.

The log will show now what has happened.

Finished scan

Saved event cache at /Volumes/Time Machine Backups/Backups.backupdb/z87proimac/2018-01-02-113204.inProgress/62C502BA-C5CB- 488F-AB71-E0D44D3EF25F/.2BB3E4A1-CE4C-350F-B8E8-E69BB22A5DE1.eventdb

Will copy (152 MB) from asusz87pro

Found 810 files (152 MB) needing backup

443.7 MB required (including padding), 287.52 GB available

Copied 1129 items (152.3 MB) from volume asusz87pro. Linked 4637.

Created new backup: 2018-01-02-115130

Starting post-backup thinning

Deleted /Volumes/Time Machine Backups/Backups.backupdb/z87proimac/2018-01-01-104923 (62.1 MB)

Post-backup thinning complete: 1 expired backups removed

Backup completed successfully.

Ejected Time Machine disk image: /Volumes/Backups.backupdb/z87proimac.sparsebundle

Ejected Time Machine network volume.

And the previous history will be noted as per before you reconfigured.

If this doesn't work for you we need to get harsher and do some more dirty stuff.

As a btw my recommendation now to everyone on Sierra and later OS.. do NOT trust Time Machine.. it is unreliable at best.. broken at worst.. and you can discover it wasn't backing up properly anyway without any indication.

Use a third party like Carbon Copy Cloner..

If you really must use Time Machine use it to local drive plugged into the computer .. eg USB. Since Sierra network backups are too problematic.

Your setup is unsupported.. ie Apple insist you use the computer directly to the TC by ethernet or wireless.. not via another router like your C7.

Sorry I ran out of edit time..

I see you did actually attempt to connect directly to the TC..

I tried changing our wireless network configuration so that Computer 2 was directly connected to the Time Capsule. We have a newer wireless router with better range, so we use that for our wireless network and have the Time Capsule in bridge mode with the wireless off. I turned the wireless back on and connected computer 2 to that network, but that didn't seem to make much difference.

The somewhat different failure on the direct connection.. still leads me to the same advice.. start with the full reset of TM..

No luck with that.. then you will need to factory reset the TC..

Setup from the computer that has issues..

Give it a new name.. short, no spaces and pure alphanumerics. Bonus points for names <10 characters.

Passwords same rules.. but 8-29 characters depending on your level of paranoia.. or even more if you love typing. Still mixed case and numbers only.

I am not at all happy that the auto setup uses the same password for both wireless and admin access. Since I am constantly resetting a bunch of airports to give answers in these threads I do use it that way.. but consider carefully if you need security .. and everyone who has access to wireless also has the TC password is not so great.

The problem with doing the above is you will now mess up TM on MBP1 which will need you to redirect it to the new network name.. and is just as likely to start causing issues on MBP1 and you will land in the same boat as now.

Due to changes in DNS in later versions of Mac OS.. you are likely to have this happen a week after going through this whole procedure.. so fixes can be temporary at best.

To say nothing of the dreaded.. TM fouling its own nest.. and doing a complete wipe.

This backup was to a TC following all the above rules.. it wiped out 12months worth of backups.. and happens pretty much annually. I have decided it is now time... after using CCC for a few years.. and being very happy with it.. I moved from Time Machine as primary to CCC as my primary backup software.. I now run TM for purely cosmetic and test purposes.

Do you use that to backup to the Time Capsule?

Yes, CCC is very flexible.. you can back up just like Time Machine to local disk.. which is actually preferred because you can create a bootable clone.. or to the Time Capsule using a Sparsebundle in the same way Time Machine does.

But the backup is very different in that instead of a string of dates with each backup as TM would produce.. CCC is still doing a clone of the computer.

It does include a system of backing up old files though.. so if a file has changed.. the old version goes into the safety net for that day..

The great thing with a bootable clone.. is if the computer fails.. you can boot the same computer or another similar one directly from the backup.. with an exact copy of your setup as per the last date of the backup.