Try reinstalling?
Also, you can do the update automatically, try this script:
Code:
#!/bin/bash
calibre-debug -c "import urllib as u; from calibre.constants import numeric_version; raise SystemExit(int(numeric_version < (tuple(map(int, u.urlopen('http://calibre-ebook.com/downloads/latest_version').read().split('.'))))))"
UP_TO_DATE=$?
if [ $UP_TO_DATE = 0 ]; then
echo "Calibre is up-to-date"
else
killall calibre
killall calibre
sudo python -c "import sys; py3 = sys.version_info[0] > 2; u = __import__('urllib.request' if py3 else 'urllib', fromlist=1); exec(u.urlopen('http://status.calibre-ebook.com/linux_installer').read()); main(install_dir='/opt')"
fi
Then put that in your crontab.

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