--TEST-- Bug GH-9866 (Time zone bug with \DateTimeInterface::diff()) --FILE-- diff($endDate, true); return $dateInterval->y; } $start = new \DateTimeImmutable('2000-11-01 09:29:22.907606', new \DateTimeZone('America/Chicago')); $end = new \DateTimeImmutable('2022-06-06 11:00:00.000000', new \DateTimeZone('America/New_York')); $result = getYearsBetween($start, $end); var_dump($result); $diff = $start->diff($end); echo $diff->format("%R %Y %M %D (%a) %H %I %S %F"), "\n"; ?> --EXPECT-- int(21) + 21 07 04 (7886) 23 30 37 092394