[11:44:49] [Server thread/WARN] [FML]: Forge Mod Loader detected missing blocks/items.

There are 2 missing blocks and items in this save.
If you continue the missing blocks/items will get removed.
A world backup will be automatically created in your saves directory.

Missing Blocks/Items:
biomesoplenty:moss
biomesoplenty:moss

Run the command /fml confirm or or /fml cancel to proceed.

Is there any release note that we can find those new or removed blocks?

Moss got removed in e949c22 , it's fully intended. Just run /fml confirm.

Oh Thanks :)