This is a problem that has been hanging around for a long time:

All the text fields retrieved from XML files (OVF for example) should be truncated to the maximum size of the fields allowed in the database. For example, if the description of a Virtual Image is longer than 255, the download process completes, it does not report any error, but the image is not published in the local repository because the insertion fails because of this problem.

Two options here:

1) change all the 'description' fields from VARCHAR to TEXT type
2) truncate the string fields to the maximum allowed size of the field.

Option two is the correct one.