AVRdude Verification Error Solution
If you’ve been getting an Arduino error like this:
avrdude: verifying ... avrdude: verification error, first mismatch at byte 0x0007 0xff != 0x7f avrdude: verification error; content mismatch
It may be as simple a fix as moving your USB cable from a hub directly to your computer—that fixed it for me!
More information: I had also been getting errors like this from avrdude:
avrdude: 2 retries during SPI command