Hesitant to post, incase its something unique with my setup but, using latest XAMPP as the stack for testing this extension in mediawiki, i've come across an internal error when trying to upload and convert.
Stacktrace details below, and hoping these might be useful.
_[f4c0923d8d4858b2cd7f07c1] /mediawiki/index.php/Special:PandocUltimateConverter Error: Call to a member function getLocalRefPath() on bool
from C:\xampp\htdocs\mediawiki\extensions\PandocUltimateConverter\SpecialPandocUltimateConverter.php(119)
#0 C:\xampp\htdocs\mediawiki\extensions\PandocUltimateConverter\SpecialPandocUltimateConverter.php(84): SpecialPandocUltimateConverter::convertFileToPage(string, string)
#1 C:\xampp\htdocs\mediawiki\includes\htmlform\HTMLForm.php(751): SpecialPandocUltimateConverter::processForm(array, HTMLForm)
#2 C:\xampp\htdocs\mediawiki\includes\htmlform\HTMLForm.php(631): HTMLForm->trySubmit()
#3 C:\xampp\htdocs\mediawiki\includes\htmlform\HTMLForm.php(647): HTMLForm->tryAuthorizedSubmit()
#4 C:\xampp\htdocs\mediawiki\extensions\PandocUltimateConverter\SpecialPandocUltimateConverter.php(75): HTMLForm->show()
#5 C:\xampp\htdocs\mediawiki\includes\specialpage\SpecialPage.php(727): SpecialPandocUltimateConverter->execute(NULL)
#6 C:\xampp\htdocs\mediawiki\includes\specialpage\SpecialPageFactory.php(1621): MediaWiki\SpecialPage\SpecialPage->run(NULL)
#7 C:\xampp\htdocs\mediawiki\includes\MediaWiki.php(357): MediaWiki\SpecialPage\SpecialPageFactory->executePath(string, RequestContext)
#8 C:\xampp\htdocs\mediawiki\includes\MediaWiki.php(960): MediaWiki->performRequest()
#9 C:\xampp\htdocs\mediawiki\includes\MediaWiki.php(613): MediaWiki->main()
#10 C:\xampp\htdocs\mediawiki\index.php(50): MediaWiki->run()
#11 C:\xampp\htdocs\mediawiki\index.php(46): wfIndexMain()
#12 {main}_