This article explains how you can get or create a digital signature for use in Office documents. To learn more about how to use them in Office documents, see Add or remove a digital signature in Office files.

If some Windows functions aren't working or Windows crashes, use the System File Checker to scan Windows and restore your files. Though the steps below might look complicated at first glance, just follow them in order, step-by-step, and we’ll try to get you back on track. Run the System File Checker tool (SFC.exe)

Learn how to update your security processor or TPM firmware to protect Windows 10 and your device from attacks by malicious software.

Having trouble connecting to your email from Outlook on your desktop? Follow these steps to let Outlook diagnose and fix errors in your Outlook mail profile that might be causing the issue.

This article describes how you can digitally sign a macro project on Windows by using a certificate. If you don't already have a digital certificate, you'll need to get one. Tip: To use or test macro projects on your own computer, you can create your own self-signing certificate by using the Selfcert.exe tool.

Some Office 2019, Office 2016, and Office 2013 products come with a product key. If yours did, before installing Microsoft 365 for the first time, sign in with an existing or new Microsoft account and enter your product key at office.com/setup. Redeeming your key is what links your account with Microsoft 365 so you only have to do this once.

This security update resolves a Microsoft Excel remote code execution vulnerability and Microsoft Office information disclosure vulnerability. To learn more about the vulnerabilities, see the following security advisories: Microsoft Common Vulnerabilities and Exposures CVE-2021-31174.

If you already redeemed a product key, you're simply reinstalling the apps, or you know you have an assigned license through work or school, you can skip ahead and go to the section sign in to download and install Microsoft 365 or Office.

What do certificate errors mean? Is it ever safe to ignore a certificate error? Can I go to a site even if I get a certificate error? Can I turn off certificate errors? Learn about certificate errors in Internet Explorer: what they are, what they mean, and what you should do about them.

Download the offline installer from your account portal. To download the offline installer, go to www.office.com. If you're not already signed in with the Microsoft account associated with your copy of Microsoft 365 or Microsoft 365 do that now.