Microsoft Office 365, Office 2019 and Office 2016 are widely used across operating systems. Microsoft Office is the best productivity suite money can buy right now. Activating or reactivating Office products is easy. If using Office 365, you can simply sign in with the Microsoft account that you used to purchase Office 365 subscription to activate your copy of Office 365 on your PC. If you are using Office 2019 or 2016, you will need to either enter the product key that you received when you bought Office 2019/2016 or sign in with the email address that you used to buy the product. When the Office activation fails, you see Unlicensed product or Non-commercial use/Unlicensed product message in the title bar of Office applications. Besides that, most features of Office are disabled when using it without activation. If you are unable to activate your copy of Office 365/2019/2016 and wondering why the activation fails, you can try out the official Office 365 and Office 2019/2016 activation troubleshooters. Just like there is an activation troubleshooter out there for Windows 10, there is one for Office as well. Office 365/2019/2016 Activation troubleshooter There is a dedicated activation troubleshooter for Office 365/2019/2016. The troubleshooter is compatible with Office Home & Student, Office Home & Business, Office Professional, and individual apps like Project, Word, and Outlook. Visit this Office support page link to download the troubleshooter. Run the same and follow the on-screen directions to fix Office 365/2019/2016 activation errors. It’s worth noting that the Office support page says that this troubleshooter is meant for non-subscription Office products. However, the troubleshooter itself says that it’s for Office 365 and Office 2016. So, you can use for Office 365, Office 2019 and Office 2016. Another Office 365 troubleshooter The official Support and Recovery Assistant for Office 365 allows you to troubleshoot activation issues. However, the Support and Recovery Assistant is for Windows only, and it doesn’t support Office 2019 and 2016. In addition to activation issues, Support and Recovery Assistant can also be used to troubleshoot Office 365 installation, Outlook, OneDrive for Business, Dynamics 365 and Skype for Business issues. The tool is the best tool out there to troubleshoot Outlook issues. Here is how to download and use it to fix Office 365 activation errors. Step 1: Visit this link to download Support and Recovery Assistant for Office 365. It actually downloads the web setup. Step 2: Run the web setup to download and start the Support and Recovery Assistant. Step 3: Run the Support and Recovery Assistant, accept the license terms. Follow the on-screen directions to troubleshoot your Office 365 activation issues.