Overcoming Installation Error 0x800F081F for .NET Framework 3.5 During Office 2021 Setup

Encountering error code 0x800F081F during Office 2021 setup? Here are several effective solutions to fix it:

1. Method 1: Install .NET Framework 3.5 manually
• Press the Windows key + R to open the Run dialog box.
• Type 'appwiz.cpl' and press Enter to open the Programs and Features window.
• Select 'Turn Windows features on or off' on the left-hand side.
• Tick the box next to '.NET Framework 3.5 (includes .NET 2.0 and 3.0)' and click OK.
• Follow the on-screen instructions to install .NET Framework 3.5.
2. Method 2: Use the DISM tool
• Open the Command Prompt with administrative privileges.
• Type this command and press Enter: DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:X:\sources\sxs(Note: Replace 'X' with your Windows installation media's drive letter.)
• Wait for the process to finish and restart your computer.
3. Method 3: Use the Windows Update Troubleshooter
• Open the Settings app and go to Update & Security.
• Select Troubleshoot on the left-hand side.
• Click on Windows Update and then on Run the troubleshooter.
• Follow the on-screen instructions to finish the troubleshooting.
4. Method 4: Temporarily disable antivirus software
• Open your antivirus software and temporarily disable it.
• Attempt to install Office 2021 again.
• Once installation is complete, re-enable your antivirus software.
5. Method 5: Perform a clean boot
• Press the Windows key + R to open the Run dialog box.
• Type 'msconfig' and press Enter to open the System Configuration window.
• Click on the Services tab and check the box next to 'Hide all Microsoft services.'
• Click on Disable all and then click on OK.
• Restart your computer and try installing Office 2021 again.
• After installation, return to the System Configuration window and click on Enable all.
• Restart your computer again.