diff --git a/server/channels/app/shared_channel.go b/server/channels/app/shared_channel.go
index c25f03e3071..f861265c789 100644
--- a/server/channels/app/shared_channel.go
+++ b/server/channels/app/shared_channel.go
@@ -339,6 +339,7 @@ func (a *App) ReceiveSharedChannelAttachmentSyncMsg(rctx request.CTX, pluginID,
 		Filename:  fi.Name,
 		FileSize:  fi.Size,
 		RemoteId:  rc.RemoteId,
+		ReqFileId: fi.Id,
 	}
 
 	us, appErr := a.CreateUploadSession(rctx, us)
diff --git a/server/channels/app/shared_channel_test.go b/server/channels/app/shared_channel_test.go
index 73adac0c1b3..5acdc384fc1 100644
--- a/server/channels/app/shared_channel_test.go
+++ b/server/channels/app/shared_channel_test.go
@@ -1360,7 +1360,11 @@ func TestPluginAPIReceiveSharedChannelAttachmentSyncMsg(t *testing.T) {
 		remoteUser, appErr := th.App.CreateUser(th.Context, remoteUser)
 		require.Nil(t, appErr)
 
+		// The sender-side file ID must be preserved on the receiving server so the
+		// post's FileIds (which reference the sender ID) resolve to the saved file.
+		senderFileID := model.NewId()
 		fi := &model.FileInfo{
+			Id:        senderFileID,
 			CreatorId: remoteUser.Id,
 			Name:      "hello.txt",
 			Size:      13,
@@ -1369,12 +1373,13 @@ func TestPluginAPIReceiveSharedChannelAttachmentSyncMsg(t *testing.T) {
 		saved, err := api.ReceiveSharedChannelAttachmentSyncMsg(rc.RemoteId, channel.Id, fi, bytes.NewReader([]byte("hello, world!")))
 		require.NoError(t, err)
 		require.NotNil(t, saved)
-		assert.NotEmpty(t, saved.Id)
+		assert.Equal(t, senderFileID, saved.Id, "saved FileInfo must keep the sender's file ID")
 		assert.Equal(t, rc.RemoteId, *saved.RemoteId)
 
 		// Verify the FileInfo was persisted with a server-constructed path
 		storedFI, appErr := th.App.GetFileInfo(th.Context, saved.Id)
 		require.Nil(t, appErr)
+		assert.Equal(t, senderFileID, storedFI.Id)
 		assert.Equal(t, "hello.txt", storedFI.Name)
 		assert.NotEmpty(t, storedFI.Path)
 		assert.Contains(t, storedFI.Path, "hello.txt")