When uploading a sketch you may see this warning in the console output:
Warning: Invalid DFU suffix signature
A valid DFU suffix will be required in a future dfu-util release
The message is informational and does not indicate a failed a failed upload or error.
About the warning message
The warning message is generated by dfu-util, a program used to upload sketches to some Arduino boards. The DFU suffix is a small block of data appended to the end of a firmware file that can be used to verify the firmware’s integrity and compatibility with the target device.
While a DFU suffix is recommended by the DFU standard and might become mandatory in a future version of dfu-util, it’s not currently required for successful flashing. The version of dfu-util used for sketch uploads is defined in the Arduino board platform. Any future version of dfu-util would only be adopted after verifying compatibility with the board platform.
Currently, there is no way to prevent the warning from being displayed.
How to tell if the sketch was uploaded
If you see the lines Download [=========================] 100%and Download done, it indicates that the sketch was uploaded to your board. This may be followed by a few lines of additional information, which can vary depending on the board. For example, a successful sketch upload to Arduino Portenta H7 completes with this console output:
...
Download [======================= ] 93% 147456 bytes
Download [======================== ] 96% 151552 bytes
Download [=========================] 100% 156956 bytes
Download done.
File downloaded successfully
Transitioning to dfuMANIFEST state
If the sketch upload fails, this will be indicated by other messages:
- For
Failed uploading: uploading error: exit status 74, see dfu-util errors when uploading (exit status 74). - For
Compilation error: <error description>, see If your sketch doesn’t compile.
For general troubleshooting of uploads, see If your sketch doesn’t upload.
