Brute force. When you look at the end of the URL for any forum post you’ll see a unique ID (e.g. this post’s ID is 146447). Under the assumption that that’s the same ID used in the marketplace ID I looked at some recent posts and determined this must be an older one so I started at the bottom and worked my way up until I found it.
I’m not sure where to remove it. You can look in /var/lib/openhab/jsondb in the files with “marketplace” in the name and see if it’s listed somewhere in there. If so you can stop OH, manually remove the entry, and restart OH (always take a backup first).
I removed the folder “128405” that was empty under /openhab/userdata/marketplace/bundles" and the error is gone. It seems this folder get parsed and it try to install whatever is in there. The only other folder I have is the unifi one.