Plug in manager is empty!

[FlorianPircher]

Are you located in mainland China? Then this issue might be related to the Great Firewall. See the following topic for more information:

Failled to install plugin due to "write permission"

In fact, it’s due to the GFW in China mainland. Your VPN is not reliable enough. When the https connect broken for some reason, the Git clone of the plugin manager will fail too. Then leave an empty folder (with .git info). The robustness of the plugin manager is also not so good in my point of view.