Below issue resolved by installing the component SP Simple Portfolio from the JoomShaper source site!
Just installed the PS Joomite Quickstart package with the default English sample data.
After removing the installation directory and entering the administrator side of the site I have installed the Dutch language since I want to build a Dutch site using or based on the sample data. When I open the frontend of my site I receive the error message "Unknown column 'language' in 'where clause' SQL=SELECT * FROM `woh_spsimpleportfolio_items` WHERE `enabled` = 1 AND language in ('en-GB','*') AND `access` IN (1,1) ORDER BY `ordering` ASC LIMIT 0, 8".
And indeed the column 'language' doesn't exist in this table.
It seems that the extension does not cater for different languages. Joomla allows for installing additional languages, but not removing them.
Publishing language related plugins doesn't resolve the issue.
Any advice and resolution is appreciated.