[tbb-bugs] #20795 [Applications/Tor Browser]: Torbrowser crashes if it can't DNS resolve the Socks5Proxy host in torrc

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#20795: Torbrowser crashes if it can't DNS resolve the Socks5Proxy host in torrc
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 Reporter:  gaffer206                 |          Owner:  tbb-team
     Type:  defect                    |         Status:  needs_information
 Priority:  Medium                    |      Milestone:
Component:  Applications/Tor Browser  |        Version:
 Severity:  Normal                    |     Resolution:
 Keywords:  tbb-usability             |  Actual Points:
Parent ID:                            |         Points:
 Reviewer:                            |        Sponsor:
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Comment (by mcs):

 Replying to [comment:6 gk]:
 > Thanks for the screen recording! I wonder if it would work for you if
 you clicked on "Open Settings" after you disabled your VPN and restarted
 Tor Browser but before the Tor related error message came up?

 I am not sure that will be possible. At least for me, tor exits
 immediately during startup because the proxy host cannot be resolved:
  DATE [warn] Failed to parse/validate config: Socks5Proxy failed to parse
 or resolve. Please fix.
 In the screen recording, it seemed to take a while though; I guess it
 depends on how fast the DNS lookup is for the unknown host (it might have
 to timeout if the DNS servers are unreachable).

 > mcs, brade: I wonder why the "Reconfigure" option is not shown on the
 wizard after the first error message. Wasn't #11773 for that scenario as
 well?

 I don't think this scenario was covered. The problem is that "Reconfigure"
 is only possible if tor is running. Tor Launcher could include a "Delete
 existing configuration" checkbox (or a second restart button) on that
 "Restart Tor" wizard screen. If that option was chosen, Tor Launcher would
 zero out the torrc file before trying to start tor.

 The best solution might be to use a separate browser profile when
 connected to the corporate network (I know that might be inconvenient).

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20795#comment:7>
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