# System Requirements and Installation

Source: [https://docs.virtosoftware.com/docs/virto-calendar-web-part/system-requirements-and-installation/](https://docs.virtosoftware.com/docs/virto-calendar-web-part/system-requirements-and-installation/)
Product: Virto Calendar Web Part
Updated: 2026-08-12

## Pages
- [Error “Sorry, apps are turned off”: what to do](https://docs.virtosoftware.com/docs/virto-calendar-web-part/system-requirements-and-installation/error-sorry-apps-are-turned-off-what-to-do/index.md) — Why SharePoint 2019 refuses the calendar with the apps are turned off error, and how to fix each cause.
- [Expected outage](https://docs.virtosoftware.com/docs/virto-calendar-web-part/system-requirements-and-installation/expected-outage/index.md) — How long a farm is unavailable while the Virto Calendar web part is installed or upgraded.
- [Installing the Virto Calendar SPFx web part and Mini Calendar](https://docs.virtosoftware.com/docs/virto-calendar-web-part/system-requirements-and-installation/installing-the-virto-calendar-spfx-web-part-and-mini-calendar/index.md) — Installing the SPFx package for modern SharePoint 2019 pages, starting with a tenant app catalog.
- [Installing the Virto Calendar web part](https://docs.virtosoftware.com/docs/virto-calendar-web-part/system-requirements-and-installation/installing-the-virto-calendar-web-part/index.md) — Privileges and server access needed to run the calendar setup, and the components it installs.
- [System and developer requirements](https://docs.virtosoftware.com/docs/virto-calendar-web-part/system-requirements-and-installation/system-and-developer-requirements/index.md) — Server, browser and .NET requirements, listed separately for each supported SharePoint release.