If you see RX10 but the latest is RX13, you need to apply three sequential UPDs (RX10->11, 11->12, 12->13) unless the repacker provides a "mega UPD."
Critical Warning: Never skip versions. Jumping from RX10 directly to RX13 via a "cumulative patch" without the intermediate files will break your character skin textures. koikatsu partyrepack upd
This is where 90% of users fail.
Pro Tip: Also copy \abdata\list\ if you created custom mod lists. If you see RX10 but the latest is
You downloaded Koikatsu Party Repack R7 (or R8, R9). It works fine. But a month later, new DLC (like the After School or Sunshine cross-mod) drops, or a major plugin like KK_MakerAdditions breaks due to a Windows update. Critical Warning: Never skip versions
The Upd (short for Update) files are incremental patches released by the repack creator. They are not auto-downloaded. You must manually apply them.
Cause: The UPD only updates the core engine. Mods are separate. Fix: Run KKManager -> "Sideloader Modpack" tab -> "Sync to disk." This downloads the new clothing and items.