After updating from FB 2.1.3 to F 2.5 we've got some troubles with adding values to timestamps.
Following statement runs on FB 2.1.3 without problems (ISO8859_1):
SELECT CAST('01.01.0200 12:00:00' as timestamp) + 1 from rdb$database
On F 2.5 we've got 'value exceeds the range for valid timestamp'
The first timestamp value that is working on FB2.5 is November 16, 1858