You need three distinct NSP files:
You mentioned "p upd" in your search. This refers to the Patch or Update file. For Diablo III, installing the update is crucial for two reasons:
Many users download the base NSP, install the UPD, and launch the game only to find a black screen after the title logo. This is almost always caused by missing language data.
Here is the technical breakdown:
If you skip the language pack, the update (UPD) will try to reference audio files that do not exist on your system, resulting in the infamous "The software was closed because an error occurred" crash.
Assuming you have a hacked Switch running Atmosphere 1.5.0+ with Sigpatches, follow this precise order:
Use a title installer like DBI, Tinfoil, or Goldleaf.
For users managing Diablo III: Eternal Collection files:
Here is where things get interesting for the international community. Diablo III on Switch is a large game. To save space on the internal memory, Nintendo and Blizzard separated the voice-over and text languages into DLC-style Language Packs.
If you have ever downloaded a European or Japanese NSP and wondered, "Why is my menu in Japanese?" — you are missing the Language Pack Update.
The "P" Update (often labeled in scene releases as [v0] or [Update][v65536]) typically refers to the patch that enables:
Pro Tip: If you install the base NSP but the dialogue is silent or the text is glitched, you haven't installed the "Language Pack DLC" . It is a separate [NSP] file usually named [01001B300B9BF005][v0].nsp.