diff --git a/lib/shared/messages/reaction-message-spec.js b/lib/shared/messages/reaction-message-spec.js
--- a/lib/shared/messages/reaction-message-spec.js
+++ b/lib/shared/messages/reaction-message-spec.js
@@ -2,6 +2,7 @@
 
 import invariant from 'invariant';
 
+import type { PlatformDetails } from '../../types/device-types';
 import {
   assertMessageType,
   messageTypes,
@@ -10,8 +11,10 @@
   type RawReactionMessageInfo,
   type ReactionMessageInfo,
 } from '../../types/message-types';
+import type { RawUnsupportedMessageInfo } from '../../types/messages/unsupported';
 import type { RelativeUserInfo } from '../../types/user-types';
 import { messagePreviewText } from '../message-utils';
+import { hasMinCodeVersion } from '../version-utils';
 import type { MessageSpec, MessageTitleParam } from './message-spec';
 
 export const reactionMessageSpec: MessageSpec<
@@ -90,5 +93,27 @@
     };
   },
 
+  shimUnsupportedMessageInfo(
+    rawMessageInfo: RawReactionMessageInfo,
+    platformDetails: ?PlatformDetails,
+  ): RawReactionMessageInfo | RawUnsupportedMessageInfo {
+    // TODO: change minCodeVersion to correct number when ready
+    if (hasMinCodeVersion(platformDetails, 999)) {
+      return rawMessageInfo;
+    }
+    const { id } = rawMessageInfo;
+    invariant(id !== null && id !== undefined, 'id should be set on server');
+
+    return {
+      type: messageTypes.UNSUPPORTED,
+      id,
+      threadID: rawMessageInfo.threadID,
+      creatorID: rawMessageInfo.creatorID,
+      time: rawMessageInfo.time,
+      robotext: 'sent a reaction',
+      unsupportedMessageInfo: rawMessageInfo,
+    };
+  },
+
   generatesNotifs: true,
 });