Kurt Shintaku's Blog

Every so often this question comes along:

• “We need to install Office on a server to allow a server-side application to process Office documents."
• “We want to install Word on our server to take .DOC files and export them to Adobe Acrobat .PDF".”
• “Can we install Excel on a server to run macros to automate work on a server?”
• “We have a server-based application that requires the installation of Office to use the Office libraries. How do we install it?”

FYI using Office on servers is discouraged because the product isn’t designed for server-side processing with multiple CPUs & multiple simultaneous users / threads nor is it designed for secure, unattended operation.

From our documentation:

Microsoft does not currently recommend, and does not support, Automation of Microsoft Office applications from any unattended, non-interactive client application or component (including ASP, ASP.NET, DCOM, and NT Services), because Office may exhibit unstable behavior and/or deadlock when Office is run in this environment.

If you are building a solution that runs in a server-side context, you should try to use components that have been made safe for unattended execution. Or, you should try to find alternatives that allow at least part of the code to run client-side. If you use an Office application from a server-side solution, the application will lack many of the necessary capabilities to run successfully. Additionally, you will be taking risks with the stability of your overall solution.

…

Licensing Office for server-side use is also different. 

Current licensing guidelines prevent Office applications from being used on a server to service client requests, unless those clients themselves have licensed copies of Office. Using server-side Automation to provide Office functionality to unlicensed workstations is not covered by the End User License Agreement (EULA).

Details of the operational & licensing considerations are located here:

• Considerations for server-side Automation of Office
  https://support.microsoft.com/en-us/help/257757/considerations-for-server-side-automation-of-office