If you enable logging and FTP access to your Web App you get access to a directory tree with different formats of logs. I couldn't view the Failed Request Traces because browsers are highly suspicious of XSL files because they can contain malicious processing instructions

So step 1 is download the failed request XML file and also the freb.xsl file

Next use xsltproc to create a html file

xsltproc freb.xsl fr000003.xml  > out.html

Open in your favourite browser and enjoy