CTAP is the GameID of many unused 3DS applications. For some reason, the data varies.

What is this?

Many titles just show the exception occured message when booted.

The filesystem

After inspecting in GodMode9, many CTAPs are missing an ExeFS, or even a RomFS, explaining why they show the exception occured message. They usually have random data, none of which has been attempted to been opened. There are 4 just containing .FIRM files in the ExeFS. One boots the normal menu, another just hangs, and the other two show a glitchy screen before showing a Japanese error, despite being tested on a European console.