Cannot reconnect after upgrading to Yosemite

Question

I’m having trouble reconnecting to my Time Capsule.
Here’s the situation: The Time Capsule remains connected all the time. About 2 months ago, my old one died and I bought a new one, but it has worked fine.
In addition to the backup on the Time Capsule, every month or so, I plug a separate portable hard drive into my computer and let it do an update to my Time Machine, selecting it in “Open Time Machine Preferences.” After it does its update, I disconnect it and tell Preferences to go back to using the regular Time Machine, which it calls Data. Every time, a window pops up asking me for the password for the Data drive, but that is already filled in, so I just click OK and it connects.
Last week, however, I upgraded to OS Yosemite. No problem with regular backups. Then this week I did my secondary backup to the second HD. Then when I went back to Data, the password was not filled it. I put it in and clicked OK. Then, for the first time ever, it asked for a backup password for “Robert_iMac_3.06_GHz_XXXX”, (last for digits changed) which I assume is the name of my computer. I put in the normal administrator password, but it says “Password incorrect. Try again.” I’ve tried about every password I use, including "public," but nothing works. Again, I’ve never before been asked for a password at this stage of reconnecting the Time Machine.
Any suggestions?

Answer 1

I have not seen this one reported.. it is really odd that it worked and then stopped.
I would suggest you reset Time Machine..
A4 here has the info but it is getting out of date.
http://pondini.org/TM/Troubleshooting.html
I would also manually mount the sparsebundle in the computer just to ensure that is possible.
The info is there in A5 and under the FAQ, try Q15-17 which shows some of the manual access info.
No luck.. you are probably going to have to archive off the old backups and start again..
Since Mavericks I have been warning people to start using a different backup software.. in addition if you like to TM. It is becoming too flakey to trust.. especially to recover.. works great when it works.. when it fails it causes more pain than is warranted. Carbon Copy Cloner is what I picked.. works extremely well because you can do bootable clones.. instantly test the validity of the backup by booting off it. IMHO that makes life a lot easier than TM where you cannot know the backup is good until the day of crisis unless you go through a heap of pain to test it.