I recently upgraded from Kubuntu 14.10 to 15.10 (via 15.04) with Plasma 5.4. The migration from KDE SC 4 to Plasma 5 went rather smoothly (except for some weird hiccup while migrating kwallet... but that still kept working with all applications).
I am experiencing a problem setting up my Google Hangouts account with telepathy on my main workhorse machine. On a different machine with the same distro, it works.
I can add the Google account from System Settings -> Online Accounts via the Google Web UI Snippet. Clicking "configure" next to the account, crashes system settings, but that is a different bug entirely.
After adding the account, clicking the red human silhouette icon in the system tray and then on "go online" just leads to an error message telling me it cannot authenticate: "Authentication of your account failed (is your password correct?"
All the bug reports I found pertaining to this subject seem to say that "it works first, only to subsequently crap out with the message above." So that can't be it, since for me it doesn't work at all.
I compared all telepathy and kde-telepathy packages installed on both machines and they are identical.
In order to exclude a purely configurative problem, I set up a new user account on the problematic computer and tried to set up a new account there. That failed as well, with the same error message.
My suspicion is that the problem has something to do with the packages/config on the machine in question. But I do not know how to best debug this. Any help will be greatly appreciated. . Thanks