warning: checkdate() expects parameter 3 to be long

Having the same issue. I'll post a patch if I can track down the bug.

Looks like it's running both the start and end date through the validation. If you don't have a year set for the end date (or for either, for that matter), it's trying to send an empty string to checkdate, which complains because it expects an integer.

Unfortunately, the end date is sent for validation even if you don't check the 'Event has end date' box, which is the root of the problem.

Not sure if this is the right approach generally, but here's a patch that works for my purposes.

I added a #skip_validate property to the event form element, which can be set to true in forms where you don't want validation to instantly apply. Then, in hook_form_alter for the node_form, I set that prop to true for the second date. Then implemented event_validate_form to examine the checkbox and validate the element only if it was checked.

here is a very simple patch to have the end validation only run if the end date checkbox is checked. If i understand the problem this is a much smaller fix for the same problem.

The end date has a default date send which should not affect the validation process. Can somebody try to add casts to ind in the checkdate call?

ie:

if (!checkdate((int)$form['#value']['month'], (int)$form['#value']['day'], (int)$form['#value']['year'])) {
form_error($form, t('The specified date is invalid.'));
}

I've applied gengel's patch with modifications.