With 1.4.0, I had an additional entry on $wgNavigationLinks:
array( 'text'=>'sandbox', 'href'=>'sandbox-url' ),
with WikiMedia:Sandbox contaning "Sandbox" and WikiMedia:Sandbox-url containing "Hobbes:Sandbox" (Hobbes is the name of my project).
Suddenly, upgrading to 1.4.1 makes it fail: the Navigation box shows "<sandbox>" and its contents points to "--error:_link_target_missing--".
Any idea what's happening?