Impossible to select "- All -" on multi value field "An illegal choice has been detected. "

I think i have the same issue.

I have one multi value field which i want to be exposed for the user.

If i select "- All -" from the list, it seems to be not really the selected anything, because the view gives out this error message: "An illegal choice has been detected."

When i visited this view on the front end and look into the html sources, there is just no value selected. Only if the "apply" button is pressed a value gets selected, and the error message is gone.

Settings of the exposed field:

If i click "Analyse the view" no errors were found.

Here is the part of a view with the exposed filter which gives the error message:

/* Filterkriterium: Cotent: Typ of Content (field_typ_of_content) */
$handler->display->display_options['filters']['field_typ_of_content_value']['id'] = 'field_typ_of_content_value';
$handler->display->display_options['filters']['field_typ_of_content_value']['table'] = 'field_data_field_typ_of_content';
$handler->display->display_options['filters']['field_typ_of_content_value']['field'] = 'field_typ_of_content_value';
$handler->display->display_options['filters']['field_koerperschaft_art_value']['value'] = array(
  'all' => 'all',
);
$handler->display->display_options['filters']['field_typ_of_content_value']['exposed'] = TRUE;
$handler->display->display_options['filters']['field_typ_of_content_value']['expose']['operator_id'] = 'field_typ_of_content_value_op';
$handler->display->display_options['filters']['field_typ_of_content_value']['expose']['label'] = 'Typ of Content';
$handler->display->display_options['filters']['field_typ_of_content_value']['expose']['operator'] = 'field_typ_of_content_value_op';
$handler->display->display_options['filters']['field_typ_of_content_value']['expose']['identifier'] = 'field_typ_of_content_value';
$handler->display->display_options['filters']['field_typ_of_content_value']['expose']['remember_roles'] = array(
  2 => '2',
  1 => 0,
  6 => 0,
  16 => 0,
  19 => 0,
  5 => 0,
  20 => 0,
  21 => 0,
  18 => 0,
  12 => 0,
  17 => 0,
  9 => 0,
  8 => 0,
  15 => 0,
  11 => 0,
  10 => 0,
  3 => 0,
);

As you can see the value is set to

array(
  'all' => 'all',
);

but on visiting the view, you get the error message and the html source reads:

<option value="All">- Alle -</option>

When I then just press the Submit Button on the filter it shows:

<option selected="selected" value="All">- Alle -</option>

This happens only if "All" is selected, if one or more other values are selected all went fine.