Seems you're missing files in the /admin/upgrade folder on your server. When going to that on your community, I am being met with a 404 not found error. Please go to the Client Area and download a full set of files then extract these to your local computer and upload the contents of the "ips_****" folder to your server, overwriting what is there.
Once done, go to {base-url}/admin/upgrade in your browser. Be sure to replace {base-url} with the base URL of your community.
