Cannot assign default values to checkboxes when #access is set to FALSE

I am not familiar enough with the inner workings of CCK to recommend a patch/fix.

I did apply the below work-around.

$field['#access'] = FALSE;
// Convert checkboxes (optionwidgets_buttons) to a multi select menu (optionwidgets_select).
if ($field['#type'] == 'optionwidgets_buttons') {
  $field['#type'] = 'optionwidgets_select';
}

I'm having a similar issue: getting the "illegal value" error message on a checkboxes, unlimited-value text field with ['#access'] = FALSE set via hook_form_alter.

In my case, the field is not required, and no default value is set so the field value should be null, but it looks like somehow it's being set to (integer) 1. Which, in turn, is making text.module trip up on a non-text, non-allowed value. Couldn't trace this back to the source, but hopefully this information will help someone else identify the culprit.

My workaround was to call unset($field) in hook_form_alter instead of setting #access to FALSE, which seems to be working, but I'm not sure if this is best practice.

I have the same issue. None of my checkboxes are selected, but if I set the field to #access = FALSE, I can no longer submit the form without seeing an Illegal values error. It seems to be getting the integer 1, instead of NULL.
I can confirm that the workaround in #2 works for me.

I'm having the same problem. Anyone found a fix for this?

Solution #2 fixed it for me also, but this should get fixed.

Same issue. Most frustrating.

had same isssue with onoff checkbox
workaround #765962-2: Cannot assign default values to checkboxes when #access is set to FALSE works for me

perhaps wanna check out core's #1114480: expand_checkboxes #default_value when #access=FALSE