error 1721 while installing Flight Simulator X, systemsoftware windows 8.1

Hi Jansen,

Does this issue occur only while installing Microsoft Flight Simulator?

Error 1721. There is a problem with this Windows Installer package or due to Windows installer settings.

Let’s try the following methods and check if it helps.

Method 1:

Check the Windows Installer Service.

a. Press Windows + R and type Services.msc and press Enter.

b. Scroll down and find the Windows Installer.  Double-click “Windows Installer” in the Services list.
c. On the General tab, make sure the service is started under “Service status”.
d. If the service is not already running, under Service status, click Start, and then click OK.

Unregister and re-register the Windows Installer

a. Press Windows + R and, type MSIEXEC /UNREGISTER, and then click OK. 
b. Press Windows + R and, type MSIEXEC /REGSERVER, and then click OK. After you run this command, the operation is complete.
c. Check if it helps.

Method 2:

I would suggest you to perform a clean boot and check if it helps.

Clean boot will check if any third party application is causing the issue, as clean boot helps in eliminating software conflicts.

a)    Press Windows + R Type msconfig in the search box, and then tap or click msconfig.

b)    On the Services tab of the System Configuration dialog box, tap or click to select the Hide all Microsoft services check box, and then tap or click Disable all.

c)    On the Startup tab of the System Configuration dialog box, tap or click Open Task Manager.

d)    On the Startup tab in Task Manager, for each startup item, select the item and then click Disable.

e)    Close Task Manager.

f)    On the Startup tab of the System Configuration dialog box, tap or click OK, and then restart the computer.

Note: Once you are done with the troubleshooting, perform the steps in “How to reset the computer to start as usual after troubleshooting with Clean Boot “to reset computer as usual.

Hope it helps.

Keep us posted on the status of the issue.