PHP5.3이상 공통적으로 발생

[code]

<?php

$tz = new DateTimeZone("Europe/Zurich");
$dt1 = new Datetime('2019-01-01', $tz);
$dt2 = new Datetime('2019-05-01', $tz);
echo 'EU/ZU : ' . $dt1->diff($dt2)->format('%a') . ' Days' . PHP_EOL;
echo 'EU/ZU : ' . $dt1->diff($dt2)->format('%m') . ' Months' . PHP_EOL . PHP_EOL;

$tz = new DateTimeZone("UTC");
$dt1 = new Datetime('2019-01-01', $tz);
$dt2 = new Datetime('2019-05-01', $tz);
echo 'UTC : ' . $dt1->diff($dt2)->format('%a') . ' Days' . PHP_EOL;
echo 'UTC : ' . $dt1->diff($dt2)->format('%m') . ' Months' . PHP_EOL;
[/code]

EU/ZU : 120 Days

EU/ZU : 3 Months

UTC : 120 Days

UTC : 4 Months