[OpenSearch](https://opensearch.org/) is now formally supported as an alternative to Elasticsearch. For configuration details, see [OpenSearch configuration](opensearch). This feature was developed by Matt Westcott.
* Add [`wagtailcache`](wagtailcache) and [`wagtailpagecache`](wagtailpagecache) template tags to ensure previewing Pages or Snippets will not be cached (Jake Howard)
* Filter out comments on Page editing counts that do not correspond to a valid field / block path on the page such as when a field has been removed (Matt Westcott)
* Migrate all other `data-tippy` HTML attribute usage to the Stimulus data-*-value attributes for w-tooltip & w-dropdown (Subhajit Ghosh, LB (Ben) Johnston)
* Replace `<script type="text/django-form-template"><-/script>` template approach with HTML `template` elements in InlinePanel and expanding formset (Mansi Gundre, Subhajit Ghosh, LB (Ben) Johnston)
### `ModelViewSet` automatically registers the model to the reference index
Models that are registered with a `ModelViewSet` now have reference index tracking enabled by default. This means that you no longer need to call `ReferenceIndex.register_model()` in your app's `ready()` method for such models. If this is undesired, you can disable it by setting {attr}`~wagtail.admin.viewsets.model.ModelViewSet.add_to_reference_index` to `False` on the `ModelViewSet` subclass. For more details, see [](managing_the_reference_index).
### Groups `IndexView.results_template_name` renamed from `results.html` to `index_results.html`
The `IndexView`'s `results_template_name` attribute in the `GroupViewSet` has been renamed from `wagtailusers/groups/results.html` to `wagtailusers/groups/index_results.html` for consistency with the other viewsets. If you have customised or extended the template, e.g. for [](customising_group_views), you will need to rename it to match the new name.
### Breadcrumbs now use different data attributes and events
The undocumented JavaScript implementation for the header breadcrumbs component has been migrated to a Stimulus controller and now uses different data attributes.
This may impact custom header implementations that relied on the previous approach, custom breadcrumbs that did not use `breadcrumbs` and require the expand/collapse behaviour may be impacted.
### `window.updateFooterSaveWarning` global util removed
The undocumented global util `window.updateFooterSaveWarning` has been removed, this is part of the footer 'unsaved' messages toggling behaviour on page forms.
This behaviour has now moved to a Stimulus controller and leverages DOM events instead. Calling this function will do nothing and in a future release will throw an error.
You can implement roughly the equivalent functionality with this JavaScript function, however, this will not be guaranteed to work in future releases.
### Snippets templates refactored to reuse the shared `slim_header.html` template
The templates for the snippets views have been refactored to reuse the shared `slim_header.html` template. If you have customised or extended the templates, e.g. for [](wagtailsnippets_custom_admin_views), you will need to update them to match the new structure. As a result, the following templates have been removed:
In most cases, the usage of those templates can be replaced with the `wagtailadmin/shared/headers/slim_header.html` template. Refer to the snippets views and templates code for more details.
