avrdude: verification error, first mismatch at byte 0x0042

Hello, I just uploaded a simple blink code for my arduino,and then this error apeared.

avrdude: verification error, first mismatch at byte 0x0042
0x9d != 0x24
avrdude: verification error; content mismatch

I was wondering what kind of error is this ,and how do i fix it? My arduino work fine before . im using an arduino clone called aceduino, it has an atmega 328. please help!

!!