No Social Networks are Available in Admin Settings

This happens sometimes when you are using the Mashshare Network Add-On which is disabled during update process or when you are updating from a very early Mashshare version 1.x.

Solution #

1. Disable Mashshare Network Add-On and Mashshare Share Buttons Plugin
2. Enable Mashshare THAN the Network Add-On 

All Share buttons become visible again. 
Activation order is important here!