Environment:

• Ruby: jruby 9.0.5.0 (2.2.3) 2016-01-26 7bee00d Java HotSpot(TM) 64-Bit Server VM 25.77-b03 on 1.8.0_77-b03 +jit [Windows 10-amd64]
• Gollum: Gollum 4.0.1
• Git: git version 2.7.1.windows.2

Steps:

1. Create new dir.
2. Run git init.
3. Run gollum.
4. WEBrick starts.
5. In browser access localhost:4567/, page "Create New Page" displays in edit mode "Markdown".
6. Type "Some text."
7. Push "Save" button.
8. Error page displays: "NoMethodError at /Home undefined method `objectId' for Java::OrgEclipseJgitTreewalk::TreeWalk:0x52bc2a54".
9. Page Home.md is created and committed.