diff --git a/lib/types/messages/create-sidebar.js b/lib/types/messages/create-sidebar.js
--- a/lib/types/messages/create-sidebar.js
+++ b/lib/types/messages/create-sidebar.js
@@ -14,7 +14,7 @@
   +time: number,
   +sourceMessageAuthorID: string,
   +initialThreadState: {
-    +name: ?string,
+    +name?: ?string,
     +parentThreadID: string,
     +color: string,
     +memberIDs: string[],
@@ -50,7 +50,7 @@
   +time: number,
   +sourceMessageAuthor: RelativeUserInfo,
   +initialThreadState: {
-    +name: ?string,
+    +name?: ?string,
     +parentThreadInfo: ThreadInfo,
     +color: string,
     +otherMembers: RelativeUserInfo[],
diff --git a/lib/types/messages/create-thread.js b/lib/types/messages/create-thread.js
--- a/lib/types/messages/create-thread.js
+++ b/lib/types/messages/create-thread.js
@@ -22,8 +22,8 @@
   time: number,
   initialThreadState: {
     type: ThreadType,
-    name: ?string,
-    parentThreadID: ?string,
+    name?: ?string,
+    parentThreadID?: ?string,
     color: string,
     memberIDs: string[],
   },
@@ -58,8 +58,8 @@
   time: number,
   initialThreadState: {
     type: ThreadType,
-    name: ?string,
-    parentThreadInfo: ?ThreadInfo,
+    name?: ?string,
+    parentThreadInfo?: ?ThreadInfo,
     color: string,
     otherMembers: RelativeUserInfo[],
   },
diff --git a/lib/types/thread-types.js b/lib/types/thread-types.js
--- a/lib/types/thread-types.js
+++ b/lib/types/thread-types.js
@@ -95,13 +95,13 @@
 export type LegacyThinRawThreadInfo = {
   +id: string,
   +type: ThinThreadType,
-  +name: ?string,
+  +name?: ?string,
   +avatar?: ?ClientAvatar,
-  +description: ?string,
+  +description?: ?string,
   +color: string, // hex, without "#" or "0x"
   +creationTime: number, // millisecond timestamp
   +parentThreadID: ?string,
-  +containingThreadID: ?string,
+  +containingThreadID?: ?string,
   +community: ?string,
   +members: $ReadOnlyArray<LegacyMemberInfo>,
   +roles: { +[id: string]: ClientLegacyRoleInfo },
@@ -123,14 +123,14 @@
   +thick: true,
   +id: string,
   +type: ThickThreadType,
-  +name: ?string,
+  +name?: ?string,
   +avatar?: ?ClientAvatar,
-  +description: ?string,
+  +description?: ?string,
   +color: string, // hex, without "#" or "0x"
   +creationTime: number, // millisecond timestamp
-  +parentThreadID: ?string,
-  +containingThreadID: ?string,
-  +community: ?string,
+  +parentThreadID?: ?string,
+  +containingThreadID?: ?string,
+  +community?: ?string,
   +members: $ReadOnlyArray<ThickMemberInfo>,
   +roles: { +[id: string]: ClientLegacyRoleInfo },
   +currentUser: LegacyThreadCurrentUserInfo,