Why are some users unable to get the Win10 preview?

Win10 Preview can be used to experience the features that are not available in the official version. Users can get the Win10 preview by clicking the member version in the advanced options of Windows Update, but some users can't get the preview version. Click on the above option. There is a hint to fix me, why is this?

Fault Description:

After clicking this button, it can be restored normally under normal circumstances, but some netizens have encountered the error shown in the following figure:

Reference method:

The problem may be that the system UAC is in the ghost, please enter UAC in the taskbar search box, click on the "Change User Account Control Settings" in the search results, as shown below, if the setting is the highest Level, then adjust its security level to the second one:

Then try to click “fix me”, you should get the Win10 preview.

If you set the UAC security level to the highest, you can't change the Win10 system, you can't get the Win10 preview version, so you can reduce the UAC security level by one level.