diff --git a/app/src/main/java/org/tasks/backup/BackupContainer.kt b/app/src/main/java/org/tasks/backup/BackupContainer.kt
index 3f0cc42c8..94de0c4df 100644
--- a/app/src/main/java/org/tasks/backup/BackupContainer.kt
+++ b/app/src/main/java/org/tasks/backup/BackupContainer.kt
@@ -23,32 +23,32 @@ import org.tasks.data.entity.UserActivity
 @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
 @Serializable
 class BackupContainer(
-    val tasks: List<TaskBackup>?,
-    val places: List<Place>?,
-    val tags: List<TagData>?,
-    val filters: List<Filter>?,
-    val caldavAccounts: List<CaldavAccount>?,
-    val caldavCalendars: List<CaldavCalendar>?,
-    val taskListMetadata: List<TaskListMetadata>?,
-    val taskAttachments: List<TaskAttachment>?,
-    val intPrefs: Map<String, Integer>?,
-    val longPrefs: Map<String, java.lang.Long>?,
-    val stringPrefs: Map<String, String>?,
-    val boolPrefs: Map<String, java.lang.Boolean>?,
-    val setPrefs: Map<String, java.util.Set<String>>?,
-    val googleTaskAccounts: List<GoogleTaskAccount>? = emptyList(),
-    val googleTaskLists: List<GoogleTaskList>? = emptyList(),
+    val tasks: List<TaskBackup>? = null,
+    val places: List<Place>? = null,
+    val tags: List<TagData>? = null,
+    val filters: List<Filter>? = null,
+    val caldavAccounts: List<CaldavAccount>? = null,
+    val caldavCalendars: List<CaldavCalendar>? = null,
+    val taskListMetadata: List<TaskListMetadata>? = null,
+    val taskAttachments: List<TaskAttachment>? = null,
+    val intPrefs: Map<String, Integer>? = null,
+    val longPrefs: Map<String, java.lang.Long>? = null,
+    val stringPrefs: Map<String, String>? = null,
+    val boolPrefs: Map<String, java.lang.Boolean>? = null,
+    val setPrefs: Map<String, java.util.Set<String>>? = null,
+    val googleTaskAccounts: List<GoogleTaskAccount>? = null,
+    val googleTaskLists: List<GoogleTaskList>? = null,
 ) {
     @Serializable
     class TaskBackup(
         val task: Task,
-        val alarms: List<Alarm>?,
-        val geofences: List<Geofence>?,
-        val tags: List<Tag>?,
-        val comments: List<UserActivity>?,
-        val attachments: List<Attachment>?,
-        val caldavTasks: List<CaldavTask>?,
-        val vtodo: String?,
+        val alarms: List<Alarm>? = null,
+        val geofences: List<Geofence>? = null,
+        val tags: List<Tag>? = null,
+        val comments: List<UserActivity>? = null,
+        val attachments: List<Attachment>? = null,
+        val caldavTasks: List<CaldavTask>? = null,
+        val vtodo: String? = null,
         val google: List<GoogleTask>? = null,
         val locations: List<LegacyLocation>? = null,
     )