Office 2016 For Mac Not Signing In

One of my clients currently has Office for Mac 2016 installed, which was downloaded through Office 365 with his Enterprise E3 license. He is having an issue now where he is constantly prompted to enter his username and password as shown in the below screenshot.
Re: Microsoft Office 2019 and 2016 for mac not signing in @Agnes-1030 I was able to fix the issue by doing all the mac software updates. I thought I had, but had not.

Office 2016 For Mac Support
Office 2016 Mac Sign In Not Working
Office 2016 For Mac

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Go to in a web browser. If you have purchased a Microsoft Office 365 subscription/product card or ordered the software from an online store, you have a 25-digit product key (in the form of XXXXX-XXXXX-XXXXX-XXXXX-XXXXX) on your card or receipt. Huge props to Microsoft for a very, very well done upgrade. Office 2016 feels like a completely new and very Mac-friendly application suite that might just replace Pages, Numbers, Keynote and the rest of the Apple office suite on our Mac systems here in the office. Not to mention on our Windows systems! Microsoft Office 2019 and 2016 for mac not signing in hi all. I am experiencing a weird issue. We are trying to register an office for mac 2019, we insert the key into setup.office.com, download the installer and install it, and when opening word or any app for the first time, we are presented with a sign in window for activation.

Note

Office 365 ProPlus is being renamed to Microsoft 365 Apps for enterprise. For more information about this change, read this blog post.

Symptoms

When you try to activate or sign in to any of the Microsoft Office 2016 applications after you install the version 15.33 update, you receive a blank authentication screen. Additionally, you may see any of the following symptoms.

Symptom 1

The following issues occur in the Unified Logging Service (ULS) log:

The server has redirected to a non-https URL.
Errors occur in Azure Active Directory Authentication Library (ADAL) authentication.

To locate the ULS log, open Finder and browse to the following path:

~/Library/Containers/com.microsoft.<Application>/Data/Library/Caches/Microsoft/uls/com.microsoft.<Application>/logs

Note <Application> represents the name of the application that you are troubleshooting.

Symptom 2

You notice that in an HTTP trace, the server response includes multiple WWW-Authenticate headers, such as the following:

WWW-Authenticate: Negotiate

WWW-Authenticate: NTLM

Cause

The symptoms occur for the following corresponding reasons:

Cause for symptom 1

Starting from Office 2016 for Mac version 15.33, unsecured endpoint traffic is blocked in authentication flows.

Cause for symptom 2

Starting from Office 2016 for Mac version 15.33, the authentication method no longer selects NTLM authentication when multiple WWW-Authenticate headers are present in the response. The issue occurs when the selected authentication method is unsuccessful.

Resolution

Resolution for symptom 1

Configure all authentication endpoints to use the Secure Sockets Layer (SSL) protocol.

Resolution for symptom 2

Install the September 2017 update for Office 2016 for Mac version 15.38.

More Information

More information for symptom 1

The resolution applies when you use Microsoft Active Directory Federation Services or non-Microsoft federation solutions.

Learning has never been so easy!

Simply signing into Office as another User does not change the 'Belongs to' entry in Office 2016. If the person it belongs to doesn't match the signed in person Office 2016 will start showing a licensing error.

It would be nice if there was a change owner button, or something similar, but there isn't. Luckily, it's not too hard to fix.

4 Steps total

Step 1: Open a command prompt

Use your favorite method to get a command prompt open. Winkey+R then CMD, Start then Command Prompt, etc.

NOTE - you need to run this as administrator

Step 2: Run the ospp.vbs command

Run the following command to get the last 5 digits of the product key:

Office 2016 For Mac Support

cscript.exe '%ProgramFiles(x86)%Microsoft OfficeOffice16ospp.vbs' /dstatus

Step 3: Run ospp.vbs again, different options

Run the same command again, but change the options. This time you will be unpublishing the key you found in step 2. Replace XXXXX with the key from step 2.

cscript.exe '%ProgramFiles(x86)%Microsoft OfficeOffice16ospp.vbs' /unpkey:XXXXX

Step 4: Exit command prompt, run an Office app

Once you've exited the command prompt open any Office program (Word, Excel, etc.) and you will be prompted to sign in. Whatever account you sign in with will become the 'Belongs to' account.

It only takes a few seconds to do this, but I don't know why MS made it so you have to leave the apps and go CLI for it.

References

PS script wrapper to automate these steps

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