Problem with SdFat and bitmap files

These are basic hardware read errors. The card may lockup after the first error since the transfer does not complete correctly.

The SPI bus/SD module could be marginal. What is your SPI/SD module setup.

Another possibility is a faulty SD card. This is rare. Could you try another SD card?

It is unlikely to be the card format unless the card has a corrupt file system. You might check the file system for errors on a PC.