Hacking CFW: Cias don't start, just say "An error occured... Error type: card removed"

[ZuToRuffy14]

I did everything like the 3ds.guide website instructed, everything worked perfectly until i put some games (.cia) into my cias folder.
Upon trying to install them (actually upon starting fbi or any other cia I installed during the setup) it shows this error, telling my that "The card was removed", although it isn't.
The card itself + adapter both work fine, during the setup there wasn't any problem either.
Does anyone know any solution?

 

[Joom]

Do you have the card formatted to FAT32 with a 32k byte cluster? You should also check to see if the card is corrupted.

 

[Quantumcat]

As above, https://3ds.guide/h2testw-(windows) or https://3ds.guide/f3x-(mac) to check