Please provide the full and exact command line you are using to upload with AVRDUDE 7.3.
Please also provide the full verbose output from an attempt to upload using Arduino IDE:
- Select File > Preferences... (or Arduino IDE > Settings... for macOS users) from the Arduino IDE menus.
The "Preferences" dialog will open. - Uncheck the box next to Show verbose output during:
☑compile in the "Preferences" dialog. - Check the box next to Show verbose output during: ☐ upload.
- Click the "OK" button.
The "Preferences" dialog will close. - Attempt an upload, as you did before.
- Wait for the upload to fail.
- You will see an "Upload error: ..." notification at the bottom right corner of the Arduino IDE window. Click the "COPY ERROR MESSAGES" button on that notification.
- Open a forum reply here by clicking the "Reply" button.
- Click the
<CODE/>icon on the post composer toolbar.
This will add the forum's code block markup (```) to your reply to make sure the error messages are correctly formatted.

- Press the Ctrl+V keyboard shortcut (Command+V for macOS users).
This will paste the error output from the upload into the code block. - Move the cursor outside of the code block markup before you add any additional text to your reply.
- Click the "Reply" button to post the output.