"The cause of this error message is probably due to upgrading from an older version of the Trackback plugin.

The new plugin works like this: everytime it receives a trackback ping it will look at the character encoding and convert it to UTF-8. Everytime a trackback is shown on screen it will look at the output encoding of Nucleus and either output it as a UTF-8 string, or as an us-ascii string with html entities to represent the other non-us-ascii characters. This method will ensure that the plugin is compatible with the widest range of charset encodings.

The old plugin did not do any conversion at all. It could only display trackbacks properly when they were send in the same encoding as the output of your nucleus blog. So if you received a Japanese or Chinese trackback the plugin would basically display gibberish on your weblogs.

Now back to your problem. It sounds like you converted the database structure of an older version of the plugin. The data stored in that plugin is not stored in UTF-8, which is what the newer version expects. As a result the plugin will treat the normal string as UTF-8 send it as such to the browser, which will display a XML parsing error because it receives non-UTF-8 characters when it expects to receive UTF-8.

The solution:
Well, I am not sure yet. I will probably add an upgrade plugin which converts an older database to the new format. But it is not ready yet. I'll look in to it."