Errors

Here is documentation of what error code prefix is for which module.

Nintendo 3DS

Code Module Description
001-XXXX Friends Friend Server
002-XXXX NASC Accounts (NASC)
003-XXXX AC - Auto Connection Internet Connection
004-XXXX BOSS SpotPass
005-XXXX NIM - Nintendo Installation Management Title Installation
006-XXXX NEX - Network Extension Matchmaking Servers
007-XXXX Tiger Nintendo eShop API
008-XXXX Parental Controls Parental Controls
009-XXXX Nintendo eShop App Nintendo eShop Application
011-XXXX Nintendo eShop website Nintendo eShop (website)
012-XXXX Spider Old 3DS Internet Browser
014-XXXX Cardboard System Transfer
015-XXXX OLV - Olive Miiverse
018-XXXX PIA Peer to Peer (P2P)
022-XXXX ACT - Accounts Accounts (NNID)
032-XXXX Skater New 3DS Internet Browser
090-XXXX PGL - Pokémon Global Link Pokémon Global Link
090-2415 Unknown No download server available (Monster Hunter)
090-2442 Unknown Incorrect Title key being served by the download server (Monster Hunter)

Wii U

Code Module Description
101-XXXX FP - Friend Presence Friends
102-XXXX ACT - Accounts NNID Accounts
103-XXXX AC - Auto Connection Internet Connection
104-XXXX BOSS SpotPass
105-XXXX NIM - Nintendo Installation Management Title Installation
106-XXXX NEX - Network Extension Matchmaking Servers
107-XXXX Nintendo eShop API Nintendo eShop
108-XXXX NUS/NUP??? (Unknown) Issues related to downloading updates and titles sometimes
109-XXXX Unknown Only known code is 3550, which is related to Wii Sports Club and the Nintendo eShop
110-XXXX Unknown Only known code is 3300, which occurred for some people when attempting to view special offers in the Nintendo eShop.
111-XXXX Nintendo eShop Website Nintendo eShop
112-XXXX Surf Internet Browser
115-XXXX OLV - Olive Miiverse
116-XXXX Unknown Only known code is 1819, which occurs for unknown reasons when attempting to boot Miiverse.
118-XXXX PIA Peer to Peer (P2P)
119-XXXX Vino Nintendo TVii
120-XXXX Account Settings??? (Unknown) Only 2 codes are known and they are related to attempting to use Account Settings on Pretendo
123-XXXX mintU Add-On Content Overlay App
124-XXXX EC - E-Commerce E-Commerce
126-XXXX Unknown Only known code is 9622 which occurs for unknown reasons when attempting to add funds on the Nintendo eShop.
140-0015 Unknown No download server available. (Monster Hunter 3 Ultimate)
140-0025 Unknown Download server serving incorrect CN on the certificate used by the download server. (Monster Hunter 3 Ultimate)
150-XXXX FS - File System File System
151-XXXX KPAD Wii Remote
155-XXXX SAVE Save Files
157-XXXX Unknown Unknown
160-XXXX System System
162-XXXX MCP - Memory Control Processor Title management
165-XXXX VPAD Wii U GamePad
168-XXXX NFP - Nintendo Figurine Platform amiibo
170-XXXX Softlock Softlock/Crash
199-XXXX Unidentified Unidentified error

Pretendo Network

Code Type Description
598-XXXX Juxtaposition Pretendo Network Miiverse replacement
678-XXXX Martini Pretendo legacy Miiverse patcher
727-XXXX Account Settings Pretendo Network ID Account Settings

To look for a specific error, check the official site instead: https://pretendo.network/docs/errors or type it into https://discord.com/channels/408718485913468928/415616380570697729

Page and further documentation by @spletz_ If you get an error code from a module which requires further documentation, please contact spletz_ on Discord.