To upgrade QuickBooks Desktop to a new version, ensure to stop all integrations and notify your service provider three days in advance. You may need to purchase a new QODBC Driver license if your current one is outdated. After installing the upgrade, log each user into the company file, update the file when prompted, and follow instructions to dismiss welcome banners. Each user must complete these steps for all company files they access.
For detailed steps, visit the full guide here.