avrdude: verification error, first mismatch at byte 0x0000

avrdude: verification error, first mismatch at byte 0x0000
0xff != 0x0c
avrdude: verification error; content mismatch
avrdude: verification error; content mismatch

The issue only includes avrdude verification-error output and does not identify a board, sketch, upload command, source file, or test. Start by reproducing the upload in the Arduino IDE with the same setup and collect the missing environment and steps; done would require isolating the cause of the byte-0x0000 mismatch and confirming a successful verification.

Written by the indexing model from the issue text.