Error when reading rootfs

Embedded linux on SD card, Hiding problems in many case as doubt.

• sometime kernel could not boot

Kernel panic - not syncing: No init found, Try passing init= option to kernel".

• sometime read SD card

SD card Buffer I/O error.

• sometime dd command could not done

read error or write error

Please consider it before doubt your embedded linux system.
1st,that kernel panic is evidence u-boot,grub,any boot system are maybe ok.
2nd,try mkfs against rootfs partition and write rootfs all again.
3rd,change SD card writer that using write rootfs.

In my experience mostly SD card writer are problem.
Error occur while dd command, Usually SD card problem. I used many SD card even famous brand.
But how do you believe it?

There is much much illegal copy brand.

It is little help to choice with R mark or not when you purchase SD card.
It is much case in dd command error that using without R mark SD card.
By the way how weak SD card...