13.1 Libraries Required to Display Errors

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You must notify the user of the content of errors returned by specific libraries.
The Wii U requires errors to be displayed for the following libraries. The Error Viewer also includes error messages for libraries other than the libraries listed below. Use of the Error Viewer to display error messages for those libraries is optional, but Nintendo recommends it.
File System
FS and SAVE libraries
Communication-Related
Errors in communication-related libraries (such as FP, ACT, AC, NEX, BOSS, OLV, and Pia libraries)
An exception to this rule is if the user would not be disadvantaged if the error is not displayed. Below are some examples.
When the application automatically retries an operation and completes it without any problems.
When the application can resolve the error without displaying it to the user.
During (background) processes that do not involve active user interaction and when there is no adverse effect on game progress.

Furthermore, in order to ensure smooth operation of user support services, independently changing or creating error codes is prohibited. If you wish to create your own error codes, contact Nintendo at support@noa.com in advance.
For details regarding error display, see the Wii U Error Viewer Package and the Function Reference Manuals for the libraries.
13.1.1 Handling Error Notifications

Guideline Item
The application must inform the user of the contents of errors returned by the following libraries.
File System
Communication-Related
Test Method
Cause an error in the relevant scenes and confirm the content of the error display.
Pass/Fail Determination
Passes if all of the following conditions are met.
The user is informed of the contents of the error.
The error code has not been independently created or changed.
Software to Be Tested
All applications.
Exceptions
If the following cases apply:
When the application automatically retries an operation and completes it without any problems.
When the application can resolve the error without displaying it to the user.
During (background) processes that do not involve active user interaction and when there is no adverse effect on game progress.