[tor-bugs] #28140 [Core Tor/Tor]: Our circuit died due to an invalid selected path if switching to plugabble transports

[Tor Bug Tracker & Wiki]

#28140: Our circuit died due to an invalid selected path if switching to plugabble
transports
------------------------------+--------------------
     Reporter:  gk            |      Owner:  (none)
         Type:  defect        |     Status:  new
     Priority:  Medium        |  Milestone:
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:
Actual Points:                |  Parent ID:
       Points:                |   Reviewer:
      Sponsor:                |
------------------------------+--------------------
 On the blog we got a report about a Tor notice:
 {{{
 Tor NOTICE: Our circuit 0 (id: 570) died due to an invalid selected path,
 purpose General-purpose client. This may be a torrc configuration issue,
 or a bug.
 }}}
 (see: https://blog.torproject.org/comment/278164#comment-278164)

 It turns out I can reproduce this quite often (but not always) if I switch
 to pluggable transports (e.g. the built-in obfs4 bridges) in Tor Browser
 while a page is still loading. Then I get log output like
 {{{
 Oct 22 09:41:00.000 [warn] Failed to find node for hop #1 of our path.
 Discarding this circuit.
 Oct 22 09:41:00.000 [notice] Our circuit 0 (id: 40) died due to an invalid
 selected path, purpose General-purpose client. This may be a torrc
 configuration issue, or a bug.
 Oct 22 09:41:00.000 [warn] Failed to find node for hop #1 of our path.
 Discarding this circuit.
 Oct 22 09:41:00.000 [warn] Failed to find node for hop #1 of our path.
 Discarding this circuit.
 Oct 22 09:41:00.000 [warn] Failed to find node for hop #1 of our path.
 Discarding this circuit.
 }}}
 (Note, I have no clue why the timestamp is always the same in this snippet
 but it seems this warning is emitted on a second basis and not stopping)

 This makes Tor Browser essentially unusable until one changes settings
 again or restarts.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28140>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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