That makes sense. It needs to be added in the download center info:
However, I removed palette picker, reinstalled free tools, and still had the error. I tried uninstalling free tools and reinstalling free tools, and I still had the problem. I then deleted the DW cache file, and still had the problem.
I then removed free tools and started DW again to see if the problem resolved without free tools and I got all these errors (see attached). Note the last error was displayed upon closing DW and may have actually come up twice.
After reinstalling free tools I am back to just the original one error. It looks like it is either a problem resulting from a bad uninstall routine of one of the four extensions listed above (not palette picker), or a problem with the install and perhaps uninstall routine of free tools.