Hi, I advise you to not use snapshot versions, Only use the latest stable version that you can download here: https://open.vanillaforums.com/addon/vanilla-core The latest version is 3.3 at the time I write this.
I have the same problem. Installed the latest plugin from vanilla forum and I get the "Something has gone wrong."screen. On the latest version of vanilla forums. Shame because I really wanted to use YAGA.