diff --git a/CHANGELOG.md b/CHANGELOG.md
index 155248a81..0dc536c55 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -32,6 +32,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Remote users can no longer reappear after being deleted.
 - Deactivated users may now be deleted.
 - Mix task `pleroma.database prune_objects`
+- Fixed rendering of JSON errors on ActivityPub endpoints.
 - Linkify: Parsing crash with URLs ending in unbalanced closed paren, no path separator, and no query parameters
 
 ### Removed
diff --git a/config/config.exs b/config/config.exs
index 6b513a2fe..26f039c5e 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -463,7 +463,7 @@
   enabled: true,
   limit: 5_000
 
-config :phoenix, :format_encoders, json: Jason
+config :phoenix, :format_encoders, json: Jason, "activity+json": Jason
 
 config :phoenix, :json_library, Jason
 
diff --git a/lib/pleroma/web/activity_pub/visibility.ex b/lib/pleroma/web/activity_pub/visibility.ex
index 2be59144d..986fa3a08 100644
--- a/lib/pleroma/web/activity_pub/visibility.ex
+++ b/lib/pleroma/web/activity_pub/visibility.ex
@@ -57,6 +57,7 @@ def is_list?(%{data: %{"listMessage" => _}}), do: true
   def is_list?(_), do: false
 
   @spec visible_for_user?(Object.t() | Activity.t() | nil, User.t() | nil) :: boolean()
+  def visible_for_user?(%Object{data: %{"type" => "Tombstone"}}, _), do: false
   def visible_for_user?(%Activity{actor: ap_id}, %User{ap_id: ap_id}), do: true
   def visible_for_user?(%Object{data: %{"actor" => ap_id}}, %User{ap_id: ap_id}), do: true
   def visible_for_user?(nil, _), do: false