ALM 12.01 >> Rquirement Version History not getting maintain

ALM Version: 12.01

It was able maintain requirement version history, but now getting error while access on it as well as editing it, this is happening only with requirements tab only other tabs are working fine.

AccessError: displays error message "Index was out of range. Must be non-negative and less than the size of the collection. Parameter Name: Index" and History table is blank, please refer attached file "HistoryAccessError.PNG"

Checkout Error: On each checkout Displays trice error message "String was not recognized as a valid DateTime.", please refer attached file "CheckOutErrorError.png"

Group CheckIn Table is empty not listing any checkout items, please refer attached file "GroupCheckInEmpty.png"

Individual CheckIn Error: displays error message "Index was out of range. Must be non-negative and less than the size of the collection. Parameter Name: Index" and History table is blank, please refer attached file "IndividualCheckInError.png"

Appreciate your help

BR

Hemant