another reason why UI stops working could be that there is a page/chart which does not have a label.
have a look at the file /userdata/jsondb/uicomponents_ui_page.json and verify that all pages have
a label in the section “config” which is within “value”. You can fix it there directly. Take care of permissions and ownerships and the restart OH.
(This problem can happen when you create pages through API and forget to set the label)
