[tbb-bugs] #26381 [Applications/Tor Browser]: about:tor page does not load on first start in localized Windows bundle

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#26381: about:tor page does not load on first start in localized Windows bundle
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 Reporter:  gk                                   |          Owner:  tbb-
                                                 |  team
     Type:  defect                               |         Status:  new
 Priority:  Very High                            |      Milestone:
Component:  Applications/Tor Browser             |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tbb-torbutton, ff60-esr,             |  Actual Points:
  TorBrowserTeam201806                           |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
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Comment (by mcs):

 Kathy and I spent a little time looking at this today. I am recording our
 findings here in case someone else has any idea what might be going on.
 Here is what we know:
 1. The error is due to an undefined entity with aboutTor.xhtml.
 2. We only see the problem on Windows.
 3. This problem does not occur when multiprocess mode is disabled via `set
 MOZ_FORCE_DISABLE_E10S=1`.
 4. This problem does not occur when most of Tor Launcher is disabled
 during startup via `set TOR_SKIP_LAUNCH=1`.
 5. This problem does not occur when we allow Tor Launcher to do all of its
 work but suppress the windows that it normally opens (we had to modify the
 Tor Launcher code to make this possible).

 This is all quite strange and leads Kathy and me to think that there is a
 general Firefox bug in loading of extension DTD files, e.g., maybe when
 e10s is enabled there is a race during startup which puts things in a bad
 state after Tor Launcher uses a DTD file during startup. Of course Tor
 Launcher should not be able to interfere with Torbutton in this way.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/26381#comment:4>
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