After starting Configuration the first entry on the page appears:
Warning: Declaration of renderer_plugin_siteexport_pdf::_highlight($type, $text, $language = NULL, $filename = NULL) should be compatible with Doku_Renderer_xhtml::_highlight($type, $text, $language = NULL, $filename = NULL, $options = NULL) in /srv/www/kb-it/lib/plugins/siteexport/renderer/pdf.php on line 451
but the page is usable and you can change and edit values. After pressing Save at the bottom an otherwise empty page apears, stating:
Warning: Declaration of renderer_plugin_siteexport_pdf::_highlight($type, $text, $language = NULL, $filename = NULL) should be compatible with Doku_Renderer_xhtml::_highlight($type, $text, $language = NULL, $filename = NULL, $options = NULL) in /srv/www/kb-it/lib/plugins/siteexport/renderer/pdf.php on line 451
Warning: Cannot modify header information - headers already sent by (output started at /srv/www/kb-it/lib/plugins/siteexport/renderer/pdf.php:451) in /srv/www/kb-it/inc/common.php on line 1943
After a reload Configuration appears again with a message saying "Success". Neither access_log nor error_log show anything hinting to this.
The software is DokuWiki 2018-04-22a "Greebo", language German running with PHP7 on Apache 2.4 and all updates for the plugins. Up to now I have not found any hint and without any knowledge about PHP I'm a bit confused. Can anyone lend me a helping hand?