Topic: This game card cannot be used.

I already checked if the region settings are correct and also checked if it isn't my 3ds.
Does anyone know a solution on how to fix my cartridge?

@Nekoz_2 I'm having a hard time finding anything relevant on nintendo support, which is usually a good resource. The next thing to try for troubleshooting: describe what your 3ds does, use that in the nintendo support search bar. Like, black screen, light blinking, describe what the 3ds power light does. If you get an error code, you can put error codes in nintendo support's search bar. Often, the site can tell you what they mean.

https://en-americas-support.nintendo.com/app/answers/list/st/...

In general, just as a heads up, tech questions like this may likely go unanswered in this forum.

It's been awhile since I had seen it, but is it possibly a bootleg game?
Tried cleaning the pins?

I know I remember some years ago putting in two copies of Tetris DS I have (one I already suspected was a bootleg, the other authentic) and getting a strange message with the confirmed bootleg copy. But it might have been a more generic-sounding "error" message.