I saw a lot of discussion on this topic and no clear fix (and many seem to be in older versions of Moodle).
Before the upgrade from 3.3 the marking screen would load but the document remained blank. I *hoped* an upgrade to 3.4 would correct this, but no luck. I have read the docs page over and over. What am I possibly missing?
Thank you - beating my head on concrete would be less painful...
So, with 3.3 and later you now have the option to use Google which is much easier to setup once you have set up oauth with google, which is a royal pain!
But, you have you run through all the checks in the document converter settings? Does it work there? If not, then unoconv is not set up correctly - I don't run windows so not sure about that OS but I have been able to get it running correctly on all Linux servers.
I failed to mention that I do have the Google Document converter enabled, so after reading your message I made the Unoconv "Hidden" on the Manage Document Converters Screen. When I test the Google Document Converter, it says that it is configured properly and I do get the test page to load.
However, when I open an assignment to grade it, I get the message "Generating PDF" but the text never appears and I just have a blank screen.
If you click the link below, you will be able to watch a screencast of my issue. Thanks for any thoughts.
You should also make sure the annotate pdf cron job is running, and try uploading a brand new file that has not been uploaded before, many people have mentioned having issues re-converting previously failed files (for example from before the google converter was set up). Also the google API console has a dashboard and if the error is happening on the google side than you will see an error rate on the dashboard (although I have never seen the issue to be on the google side).