occursAt sometimes failing about php-rrule HOT 2 CLOSED

Hello, interesting case. You are right that this is a timezone issue.

You are setting DTSTART with an explicit time in UTC (Z) timezone, but check_date with no time, so it picks up the time configured in your PHP instance, which I'm going to guess isn't UTC.

So if you set the time also to UTC, this should work:

'check_date' => '2023-05-01 00:00:00Z'

Alternatively, if you remove the time from DTSTART, this should also work:

$task = [
    'rrule' => 'DTSTART:20220803
RRULE:FREQ=MONTHLY;INTERVAL=3;BYDAY=1MO',
    'check_date' => '2023-05-01'
];

A 3rd option, if you set PHP timezone to UTC, this should also work:

date_default_timezone_set('UTC');
$task = [
    'rrule' => 'DTSTART:20220803T000000Z
RRULE:FREQ=MONTHLY;INTERVAL=3;BYDAY=1MO',
    'check_date' => '2023-05-01'
];

I'll admit it's a bit confusing, but essentially you have to make sure the time component of DTSTART matches exactly with the time component of the occurrence you want to check - or don't use time component at all.

from php-rrule.

Hey, thanks so much for the quick reply, it makes perfect sense that's why it's failing. Simply appending the Z to the time worked.

from php-rrule.