[Doitsu]

Originally Posted by severus

Any suggestions what can be wrong, and how to fix this? Thanks!

This message is usually being displayed if the PIL library can't be found.
Select Plugins > Manage Plugins and enable the Use Bundled Python option. If you're using an older Sigil version that doesn't come with a bundled Python interpreter, try the following:

1. Open an administrator prompt.
2. Go to the Python folder that contains pip.exe (or pip3.exe) and enter the following command:
   

   pip install Pillow

(You also might have to install beautifulsoup4 and lxml.)