I just upgraded my site to J4 and wanted to install JDownloads on it. If I go through the Joomla Install From Web tab I get the error:
Unknown column 'preview_id' in 'field list'
Error installing component
Or if I download the 4.0.42 version and upload to the site I get the same thing
Never mind. I deleted the tables from the database and tried again and it worked.