The above Microsoft office 365/2021/2019 installation Error code 30121 primarily appears when you try to open Office365,Office 2021 and 2019 Installation program on a Windows 11 and Windows10 computers It has been observed that this office installation Error code 30121 needs to repair or a reinstall the office 2021 program and you can read the below information for more knowledge.

Solutions for Microsoft office 365/2021/2019 Error Code 30121 (livesupportonlinechat.com)

error code 30121

Solutions for Microsoft Office 365/2021/2019 Installation Error Code 30121

Microsoft Office 365/2021/2019 installation programs will not open at all and gives you an Error code 1058-4. Even you get a different office Error code 30121 when you try to repair or uninstall windows. This is found on Windows 8.1 upgraded to windows11 and Windows10 machines recently.
First do a disc clean up so that we can remove old-Microsoft office 356 installation traces from your computer.

How to do disc-cleanup:-

Method-1 Creating shortcut

1. Right click on your computer home screen, Go to “new” in the list and select “Shortcut “.
2. After clicking on a shortcut, a command prompt windows update will open and type the command “cleanmgr.exe” in it and name as you like to remember it as a disc clean up shortcut button.
3. Then an icon will appear on your home screen, click on it and select required disc to clean up. (Normally Software gets installed on DRIVE:C which is default here).
4. Then a list of folders will appear, select temp folder, recycle bin and proceed to clean up the disc.

Meanwhile, watch this video to follow above steps for a disc cleanup.

In Conclusion,

You can also ask for System repair Image support or some Recovery help, we also restore your computer to a point when it was working fine without any issues.
Feel free to chat with us for any support. A free assistance can be provided for all the basic troubleshooting without any additional resources.