Created attachment 8681248 [details] T-BirdDateBug.jpg User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:41.0) Gecko/20100101 Firefox/41.0 Build ID: 20151014143721 Steps to reproduce: Saved a birthday (2-April-1934) to an address book entry. Actual results: Select/highlight the entry in the address book, the displayed birhday in the detail is 1 day earlier (1-April-1934). Edit the entry and the correct birthdate is displayed. Thunderbird bugs have another bug entry that stipulates two ranges where this occurs, roughly 6 months apart Mar-Apr & Sep-Oct. Expected results: The dates should be the same!
Please upgrade to thunderbird 38, where this is fixed.