Fixing an unfixable Mac Office credentials error: Kids, don't try this at home

Yes, it's a Microsoft rant. But it's a Microsoft rant with potentially dangerous but workable advice.
Written by David Gewirtz, Senior Contributing Editor

Disclaimer: If you try anything we did in this article and the sun explodes, the moon flies out of orbit, or your computer does terrible, terrible things, don't blame the author, ZDNet, CBS Interactive, or either Barack Obama or Donald Trump. It's all on you, baby. You've been warned.

Well, there went three hours of my life I'm never going to get back. Considering that even the Microsoft tech support rep gave up, and I finally got Microsoft Office 2016 for Mac to work again on my own, I'm taking the time to put this one in writing in case you encounter the same problem.

I first noticed the problem yesterday. Opening any Office application on a Mac resulted in a nasty error. In my case, the problem started happening sometime after I installed Sierra, but I can't be sure that's what caused it.

It goes something like this. Instead of launching Word or Excel, Office displays a window showing a spinning wait indicator, and then provides the error message "No credentials. The system requires that you sign on to a valid account. The error code is D000000C."


This was not fun.

Making matters more difficult, there's no way to provide any credentials to Word or Office in this situation. There's no login option, and all you can do is close the window. I did some Web searching, and I'm far from the only one with this problem.

After giving it some thought, I realized that the message might be related to the login account on the computer, rather than the Microsoft login. Since I was logged in with full admin privileges, I certainly wasn't lacking valid credentials. I was pretty convinced it wasn't that I didn't have a valid account. I was convinced it was that Office was confused.

So I uninstalled Office. As it turns out, I uninstalled and reinstalled Office a total of eight times throughout this joy ride. I tried different approaches. I went into /Library and removed all the files Microsoft recommended. I eventually found a Github script that also identified some files in ~/Library (the user account), and went through each of those files one-by-one and removed them, too.

When it didn't work from the Finder, I opened up Terminal, and sudo'd my way through the removal commands, just to be sure that it wasn't a permissions issue.

I logged into my Microsoft home account and re-downloaded and reinstalled a bunch of times. Still, over and over, I got the same error.

At this point, I realized I'd lost the will to live. This is pretty much par for the course when troubleshooting Microsoft authorization issues. I'm convinced that if Microsoft doesn't make you wish you were dead at least during some stage of using their products, they feel they haven't done their jobs. I don't know. Maybe that's a legacy of the Ballmer era. Still, not fun.

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So since I'd lost the will to live, I figured that I might as well call Microsoft tech support. Yeah, I was actually that desperate. I actually reached a rep quite quickly, but it took 41 minutes for him to verify that he did not, in fact, have a clue why I was experiencing this problem. He categorically refused to listen to what I told him I did, so I had to suffer through a screen sharing experience, the lecture about how I could quit any time, and all the rest.

He was a pleasant enough guy, but clearly in over his head. By the time we were done, he pledged to have some Level 2 tech call me back the next day. He told me I'd get a call during a time window of 2-4pm.

Given the level of total bafflement and the desire of every tech to walk you through every basic process before even paying attention, I knew it would be at least an hour before whatever so-called Level 2 tech I got on the phone would actually even listen to the details of the problem.

It became clear that if I didn't figure out the answer on my own, I'd lose another three or four hours during prime work time. It was time for a cup of coffee (butter toffee) and some thinking.

What if the error message was actually meaningful? I know, it's almost too much to ask. But what if? That would mean that Office was having some kind of difficulty with credentials.

Many credentials on a Mac are managed by the Keychain Access utility. Fueled by some quality butter toffee-favored caffeine, I decided that I might as well just nuke everything in the keychain that even seemed like it was Microsoft related.

Yes, I know. Back up. I have all my data backed up in a variety of ways, and while I don't really trust Time Machine, I did a backup before settling in with my hatchet-sized scalpel.

First, I did a search on "microsoft". Keychain Access doesn't appear to be case sensitive, so I found a number of keys. A quick right-click later and they were deleted.

Then, for good measure, I searched on "ms" and "office". I found a few keys that were clearly not related to my Office problem, but also another few that seemed to be Microsoft related. So, hey, what the heck? This is the year of living dangerously, right? So I deleted them, too.

Then, for probably the 25th time in a day, I tried launching Word. And what do you know? I didn't get the error message. I got an actual prompt to login. I typed in my user name and my password and, as if by magic, I was once again able to use Office.

I could finally get back to making my PowerPoints. Yeah, life is good. The will to live returned.

Before I end this tale of rectified woe, let me leave you with some thoughts. First, why? Why, Microsoft, must you do this to your most loyal of customers? Why? Okay, I feel better now.

For the record, I don't think even the Level 2 techs would have been able to solve the problem. Nothing I found on how to completely remove Office ever mentions the keychain, and yet there were a bunch of records just living in that thing. Microsoft definitely needs to update its removal guidelines.

But what I really want to say is that before you dig into your system and do some unmentionable and possibly irreversible tinkering, think twice. Back up. I'd say that you should call tech support, but that clearly was a bust. But, you know, be careful, okay? Baaaaad things can happen if you randomly delete system data.

So there you go. So long and thanks for all the fish.

You can follow my day-to-day project updates on social media. Be sure to follow me on Twitter at @DavidGewirtz, on Facebook at Facebook.com/DavidGewirtz, on Instagram at Instagram.com/DavidGewirtz, and on YouTube at YouTube.com/DavidGewirtzTV.

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