@gorgiselkov I believe that one might not be working because it's a skeleton plugin, and not an actual SSO auth (as stated on github page), unless you've configured it yourself but, it doesn't seem like it.

@gorgiselkov What SSO are you trying to use?

Also, try closing the nodebb app and starting it via "node app.js" and see what errors the console outputs, if any.

@gorgiselkov The integrated Node.js web server? I believe you shouldn't do that, and as the guide states, you should always use a proxy server like, in my case IIS, but as the official guide states, Nginx.
You should follow this guide in case you haven't (depending on your Servers OS):

Home - NodeBB Documentation

Does the user you're using to setup nodebb have all permissions on the subfolders where you're trying to install it? And also, you should read the errors, you can perfectly see it says on the third line of the error:

ERR! sharp Please see http://sharp.pixelplumbing.com/page/install

I think I managed to find the solution to your issue @gorgiselkov
I'm guessing you're using IIS but if not it might help as well.
Here: https://community.nodebb.org/post/72229

I managed to debug what was going on and I discovered that NodeBB was doing everything correctly and that passport was working as it should, sending the right URL to redirect to, but my HTTP Reverse Proxy (In my case a IIS server) was somehow rewriting the Location header to use the servers domain.
Managed to fix this by going into the Server settings, Application Request Routing and on the right going to the "Server Proxy Settings", and once there unchecking the "Reverse rewrite host in response headers" checkbox.

So far in my forum I have installed nodebb-plugin-sso-google, nodebb-plugin-sso-twitter and nodebb-plugin-sso-steam.
Whenever you click on any of them, you get redirected to a internal URL which gives you a 404.
You can try it yourself.

So far I have tried doing another clean install of v1.11.x (which is the one I installed on the original one) to no avail.
Does anyone know how to solve this or what's going on?

Somehow I'm having the same issue in my NodeBB forum, with all of the SSO plugins whenever I try to use them they give a 404 on a URL like /o/oauth2/ and else. Does anyone know why or how to fix it?