diff --git a/app/controllers/api/v1/accounts/conversations_controller.rb b/app/controllers/api/v1/accounts/conversations_controller.rb
index 4301eaa4a..8220f7fa8 100644
--- a/app/controllers/api/v1/accounts/conversations_controller.rb
+++ b/app/controllers/api/v1/accounts/conversations_controller.rb
@@ -160,6 +160,9 @@ class Api::V1::Accounts::ConversationsController < Api::V1::Accounts::BaseContro
 
   def conversation
     @conversation ||= Current.account.conversations.find_by!(display_id: params[:id])
+    # Return 404 if conversation has no valid contact or contact_inbox
+    raise ActiveRecord::RecordNotFound if @conversation.contact.blank?
+
     authorize @conversation, :show?
   end
 
diff --git a/app/finders/conversation_finder.rb b/app/finders/conversation_finder.rb
index d43ed31e7..b2ec2beb1 100644
--- a/app/finders/conversation_finder.rb
+++ b/app/finders/conversation_finder.rb
@@ -63,6 +63,7 @@ class ConversationFinder
     set_assignee_type
 
     find_all_conversations
+    filter_orphan_conversations
     filter_by_status unless params[:q]
     filter_by_team
     filter_by_labels
@@ -166,6 +167,12 @@ class ConversationFinder
     @conversations = @conversations.where(contact_inboxes: { source_id: params[:source_id] })
   end
 
+  def filter_orphan_conversations
+    # Filter out conversations where the contact has been deleted
+    # Using INNER JOIN is most efficient - only returns conversations with existing contacts
+    @conversations = @conversations.joins(:contact)
+  end
+
   def set_count_for_all_conversations
     [
       @conversations.assigned_to(current_user).count,
diff --git a/app/views/api/v1/conversations/partials/_conversation.json.jbuilder b/app/views/api/v1/conversations/partials/_conversation.json.jbuilder
index 6036d91e0..4cb13f543 100644
--- a/app/views/api/v1/conversations/partials/_conversation.json.jbuilder
+++ b/app/views/api/v1/conversations/partials/_conversation.json.jbuilder
@@ -3,12 +3,8 @@
 # Everywhere else we use conversation builder in partials folder
 
 json.meta do
-  if conversation.contact
-    json.sender do
-      json.partial! 'api/v1/models/contact', formats: [:json], resource: conversation.contact
-    end
-  else
-    json.sender nil
+  json.sender do
+    json.partial! 'api/v1/models/contact', formats: [:json], resource: conversation.contact
   end
   json.channel conversation.inbox.try(:channel_type)
   if conversation.assigned_entity.is_a?(AgentBot)