I have added the debug export option and reruned the report. The html file is created with its correct content in the specified tmp-directory. After that I've run the shown command.
wkhtmltopdf --version
wkhtmltopdf 0.12.1
wkhtmltopdf debug
To test wkhtmltopdf pdf generation, copy the following command into the server's command line.
myDBR saved the generated HTML file into /var/www/vhosts/domain.at/tmp/mydbr_export_1722029187.html. File size is: 28393 bytes.
$ wkhtmltopdf -O Landscape --margin-top "20" --header-spacing "8" --header-html "https://www.domain.at/mydbr/user/export_header_pdf.php" --replace rdate "04.06.2020" --replace rtime "12:00:02" /var/www/vhosts/domain.at/tmp/mydbr_export_1722029187.html debug_output.pdf
output:
The switch --header-spacing, is not support using unpatched qt, and will be ignored.The switch --header-html, is not support using unpatched qt, and will be ignored.The switch --replace, is not support using unpatched qt, and will be ignored.The switch --replace, is not support using unpatched qt, and will be ignored.QXcbConnection: Could not connect to display
Aborted