Why can't I edit a specific fieldgroup

Question

After the Upgrade from EE 2 to 3: A certain fieldgroup I can not open to change it. I have 5 fieldgroups, I can edit all, except: .../index.php?/cp/channels/fields/4 If I want to open it, I land on CP Home. A bug? What can I do?

Answer 1

Glad caching solve the issue. Actually EE 3.5.2 contains similar issue.

Editing GRID field by adding new fields or give options list to select dropdown or any other edits not affect. (Nothing changes by editing the field.)

Elislab will solve this bug in next release. Althoght, here is temporary fix for this bug by EE team: https://expressionengine.com/support/bugs/22958/Unable-to-edit-existing-Grid-field-groups

Open system/ee/EllisLab/ExpressionEngine/Controller/Channels/Fields/Fields.php and find this code on line 266:

$field->site_id = ee()->config->item('site_id');
$field->group_id = ($field->group_id) ?: 0;
$field->field_list_items = ($field->field_list_items) ?: '';
$field->field_order = ($field->field_order) ?: 0;

$field->set($_POST);

And REPLACE it with this:

$field->site_id = (int) ee()->config->item('site_id');
$field->group_id = ($field->group_id) ?: 0;
$field->field_list_items = ($field->field_list_items) ?: '';
$field->field_order = ($field->field_order) ?: 0;

unset($_POST['site_id']);
$field->set($_POST);

Answer 2

Sorry, it was only a Safari caching error. I delete the cache and the problem was solved.