When exporting to JPG, inkscape shows this error:

Traceback (most recent call last):
  File "/usr/share/inkscape/extensions/raster_output_jpg.py", line 6, in <module>
    import inkex
  File "/usr/share/inkscape/extensions/inkex/__init__.py", line 11, in <module>
    from .extensions import *
  File "/usr/share/inkscape/extensions/inkex/extensions.py", line 34, in <module>
    from .elements import (
  File "/usr/share/inkscape/extensions/inkex/elements/__init__.py", line 10, in <module>
    from ._base import ShapeElement, BaseElement
  File "/usr/share/inkscape/extensions/inkex/elements/_base.py", line 38, in <module>
    from ..styles import Style, Classes
  File "/usr/share/inkscape/extensions/inkex/styles.py", line 33, in <module>
    from .css import ConditionalRule
  File "/usr/share/inkscape/extensions/inkex/css.py", line 27, in <module>
    import cssselect
ModuleNotFoundError: No module named 'cssselect'

It won't even create a file.

Also, when exporting to TIFF

Traceback (most recent call last):
  File "/usr/share/inkscape/extensions/raster_output_tiff.py", line 7, in <module>
    import inkex
  File "/usr/share/inkscape/extensions/inkex/__init__.py", line 11, in <module>
    from .extensions import *
  File "/usr/share/inkscape/extensions/inkex/extensions.py", line 34, in <module>
    from .elements import (
  File "/usr/share/inkscape/extensions/inkex/elements/__init__.py", line 10, in <module>
    from ._base import ShapeElement, BaseElement
  File "/usr/share/inkscape/extensions/inkex/elements/_base.py", line 38, in <module>
    from ..styles import Style, Classes
  File "/usr/share/inkscape/extensions/inkex/styles.py", line 33, in <module>
    from .css import ConditionalRule
  File "/usr/share/inkscape/extensions/inkex/css.py", line 27, in <module>
    import cssselect
ModuleNotFoundError: No module named 'cssselect'

Also, It won't even create the file.

When exporting to webp:

Traceback (most recent call last):
  File "/usr/share/inkscape/extensions/raster_output_webp.py", line 6, in <module>
    import inkex
  File "/usr/share/inkscape/extensions/inkex/__init__.py", line 11, in <module>
    from .extensions import *
  File "/usr/share/inkscape/extensions/inkex/extensions.py", line 34, in <module>
    from .elements import (
  File "/usr/share/inkscape/extensions/inkex/elements/__init__.py", line 10, in <module>
    from ._base import ShapeElement, BaseElement
  File "/usr/share/inkscape/extensions/inkex/elements/_base.py", line 38, in <module>
    from ..styles import Style, Classes
  File "/usr/share/inkscape/extensions/inkex/styles.py", line 33, in <module>
    from .css import ConditionalRule
  File "/usr/share/inkscape/extensions/inkex/css.py", line 27, in <module>
    import cssselect
ModuleNotFoundError: No module named 'cssselect'

Exporting to other formats don't throw any error.

Using Linux Manjaro + KDE Plasma 5.

Any suggestions or walkthrough to solve the problem?  

Thanks in advace to everyone!

Try installing the package cssselect, I am on Arch and had to install it too, even tho it is not listed as dependency.