Question / Problem:
Above error displays attempting to import an Admin xml export file.
Answer / Solution:
This error may display if the Admin export file was created using "Save Selection" option in the export user interface. That option is intended only for silent installations and the resulting file will not import in interactive mode. For more information, refer to the following Online Help for Insight.
The following error is logged into WcfDataService log as well:
Could not read admin import file. System.ArgumentException: Version string portion was too short or too long.