It looks like it's trying to call a Python script called Base_Character.py Poser 13 uses Python 3 but older content uses older versions. It is likely an older version that isn't fully compatible with Poser 13.

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Available on Amazon for the Kindle E-Reader Monster of the North and The Shimmering Mage

Today I break my own personal record for the number of days for being alive.
Check out my store here or my free stuff here
I use Poser 13 and win 10