This guide is for Microsoft Project Professional 2021 on Windows. Project is a standalone product that installs alongside Office, and it installs most reliably next to Office of the same generation.
Before you start
- Requires Windows 10 or Windows 11, 4 GB RAM and 4 GB free disk space.
- Check any Office already on the PC. Project 2021 should sit alongside Office 2021 or Microsoft 365, in the same bit version. Open Word, go to File > Account > About Word; the top line says 32-bit or 64-bit. It will not coexist with Office 2024 or 2019.
- Have your 25-character key from the delivery email ready.
- Microsoft support for the 2021 generation ends on 13 October 2026. Project keeps working after that, but security updates stop.
Step 1: Remove any other Project version
If Project 2024, 2019 or an evaluation is installed, uninstall it under Settings > Apps > Installed apps and restart.
Step 2: Download the Project 2021 installer
Use the download link in your delivery email. It points to the official Microsoft installer for Project Professional 2021. Match the bit version of your existing Office, or choose 64-bit if the PC has no Office.
Step 3: Install
- Close all Office apps.
- Run the installer and accept the User Account Control prompt.
- Keep the PC online until you see You're all set.
Step 4: Activate Project 2021
- Open Project from the Start menu.
- Choose Enter a product key instead, or go to File > Account > Change product key.
- Enter your key and follow the prompts.
- Confirm File > Account shows Product Activated: Microsoft Project Professional 2021.
If your delivery email states your key uses phone activation, select I want to activate the software by telephone in the wizard.
Project 2021 specific problems
Error 30182 or "We found a problem" during install
The existing Office is a different generation or bit version. Install Project 2021 alongside Office 2021 in the same bit version, or move both to 2024.
"Invalid product key"
Check you installed Project Professional 2021, not 2024, not Standard, and not Visio.
Older .mpp files show a compatibility message
Normal. Project 2021 opens files from Project 2010 onwards and can save back to older formats via File > Save As.
Need help?
Stop retrying a rejected key. Screenshot the error and contact support with your order number. Your purchase is covered by our 6-month licence warranty.