I don't have the complete log to look at but this "could" be Valdiation Data Corruption issue in the source.
Personally I have had to deal with quite Validation data corruption issues in the past resuting in migration issues. And most of our issues usually used to occur when the valdiation values were added in the source by directly copying the strings from Word doc.
Deleting existing values and then adding new validation values again using "Notepad" instead of Word to copy values from, usually used to solve our issues. You may want to give that a try and see if that helps.
Some validations that come with the product appear to be configured to block being overwritten by the migrator. These validations have to be modified manually in each instance of PPM. I have never seen this message when migrating a validation that we created.