Created attachment 120858 [details] File created with 1b26e2ef0a97ded5cc812664ef8455251468e847 Steps to reproduce: 1. In a recent build of Calc set Format Cell->Number-> Category:Date Format:December 31, 1999 2. Save 3. Open in Earlier version of Calc like 4.3 or AOO
That file had a user defined date code, which it seems versions don't support. Closing as Not a Bug.