Created attachment 34291 [details] negative dates in excel and scell Example how it looks in excel and scell. Scell can be downloaded from http://scell.org/download.html
it seeams, that negative dates don't supported in actuall version of poi.
Created attachment 34292 [details] Example xlsx for negative date load file in excel and in java with poi and look at F39
It needs the support of the POI library: use 1904 date system
Can you please write a short junit unit test that highlights the problem? With no code, we have a very low chance of being able to fix bugs (if any)....
Possibly relevant: https://svn.apache.org/viewvc/poi/trunk/src/testcases/org/apache/poi/ss/usermodel/TestDateUtil.java?view=markup I believe POI supports 1900 dates, which is what Microsoft Excel uses. The xls/xslx format cannot represent earlier dates. Search the developer list and pasy bugs. I think this question has come up before for users trying to represent medieval and BC dates. https://support.office.com/en-us/article/DATE-function-e36c0c8c-4104-49da-ab83-82328b832349
Created attachment 34308 [details] junit test and small description of problem look at attached document with junit test and small description of problem.
This is related or even a duplicate of bug 45531 and bug 46411