When you see this post , probaly you have met same Surpercard DSTWO issue as I did .But my problem has been solved now , so , this post aims to show u how to solve the dstwo “An error has occured” problem .
I bought a Supercard DStwo yesterday and tried to set it up for my 3DS XL I have updated my 3ds xl Firmware to V7.1.0-16u . I reference this tutorial to done my set-up ：How to update supercard dstwo to work on 3ds V7.1.0-16 with firmware V1.25
Firstly, I downloaded the EOS Version 1.11, extracted it and put it in the root of my sd card .
Then I downloaded the firmware 1.25 and did the same, put everything in an old DS Phat and updated it succesfully.
But when I try it on my 3DS, I just get the message “An error has occured, press and hold the power button etc.”
It works fine on my old DS, but not the 3DS.
Then I kept thinking about what’s wrong with my dstwo . I am quite sure i get a decent one and also a MicroSD card reader that works well for your computer, becuase I bought them form a uas based store m they are selling the official dstwo .
At first , I thought dstwo was got blocked by the newest 3DS update.However I google it ,it said it isn’t blocked , and firmware V1.25 supports and works fine on V7.1.0-16u.
I send email to the site which I bought dstwo from ,I was paticularly surprised by they solve the problem for me !They said this issue normally happens becuase the MicroSD is failing to contact the DSTwo or data on the MircoSD has been corrupted. The method to avoid this problem is always make sure when placing EOS and games on the MicroSD you extract to desktop first and do not extract files straight to the MicroSD card or you risk corruption.
Hope it can help you ! Have a good day !