Apple Support Discussions user "Stinoke" reports:
"When I try to upload my website I get the message that there was an error during the upload. I can't figure out what error that is. I tried deleting parts of the site and pictures but it keeps giving me an error."
To solve this issue, navigate to the following files and drag them to your Trash:
- ~/Library/Preferences/ByHost/com.apple.iWeb (Note: There may be more than one of these files in this location containing a 12-digit number. You should delete them all.)
- ~/Library/Caches/iWeb/ (Drag the iWeb folder to the Trash.)
"Deleting these files reduced the number of errors that were created during the publish operation, according to the messages in my system log, but the remaining errors still precluded a successful upload.
So in addition, I made sure that within the iWeb '09 application I pulled up (ie, clicked on) each and every one of my existing web pages as if I was editing them, even though I didn't make any changes to them. I then saved the whole site back to disk before attempting to publish again.
(My intuition was that if there was some formatting conversion that iWeb '09 needed to apply to existing pages, it might not be fully applied unless the page was actually loaded for editing and then resaved.)
After this combination of procedures I was able to complete successful uploads of my site."