Ceptara

Seems like we're seeing more of this error in Windows 10:

The following Microsoft Office solution cannot be installed due to a general installer error: {name of add-in}, 0x8007007E

There is a good write up on the GoToMeeting site:
https://community.gotomeeting.com/gotomeeting/topics/windows-10-outlook-2013-plugin-install-fails

Here's a summary of the article:

On Windows 64-bit

1. Click the Windows Start button and paste %ProgramFiles%\Common Files\Microsoft Shared\VSTO\10.0\ into the search box
2. Hit Enter on your keyboard
3. Delete VSTOInstaller.exe.config

On Windows 32-bit

1. Click the Windows Start button and paste %ProgramFiles (x86)%\Common Files\Microsoft Shared\VSTO\10.0\ into the search box
2. Hit Enter on your keyboard
3. Delete VSTOInstaller.exe.config

4. Install the add-in.

On the GoToMeeting site, they also have a .bat file that automates the above steps - follow the link above to download the file.