The error is when you try to connect to an already configured tunnel.

On Fri, Nov 2, 2018, 09:39 Kalin KOZHUHAROV <me.kalin@gmail.com wrote:
On Fri, Nov 2, 2018 at 8:26 AM Laszlo KERTESZ <laszlo.kertesz@gmail.com> wrote:
> The current FDroid build (version 0.0.20181031) is broken. The Gui starts but it states "Unknown userspace Go version" and the tunnel activation action results in an error.
>
Hmm... just installed (1st time) and started it, seems fine (haven't
configured it yet).
What is your configuration?

Here: stock (no root) Android-8.1.0 (3.18.71-perf-gd0e0d1a kernel) on
XT1905 phone.

Kalin.