Frappe, pronounced fra-pay, is a full stack, batteries-included, web framework written in Python and Javascript with MariaDB (or Postgres) as the database. It is the framework which powers ERPNext. It is pretty generic and can be used to build database-driven apps.

• Installation
• Contribution Guidelines
• API Reference
• Migration Guide
• Support

To install frappe right from scratch, check official documentation.

Refer https://github.com/frappe/erpnext/wiki/Supported-Versions

This involves changes you'd have to make in your Frappe Apps to make them compatible with the latest releases of Frappe.

• Migrating to Version 13
• Migrating to Version 14
• Migrating to version 15
• Migrating to nightly version

• Discuss
• GitHub Issues
• Stack Overflow