Failed from export report to PDF

I've had this problem myself today and it was due to the layout of my report (some elements being outside the set page size). This might not be what's causing the problem for everyone, but sharing my solution in case it helps.

1. Go to the published app version of the dashboard and try exporting each page individually (there is a checkbox to do this). This should identify which page(s) is causing the problem as the export will fail on one/some pages but not all.

2. When you have identified the problematic page(s), go into Power BI desktop and open the relevant page. Make a note of the page size. Then change the page size to much bigger than that, and in the view settings, change it to 'fit to page'. This should hopefully uncover some rogue items outside of your previous page size. Delete them if they are not wanted, or move them to a suitable place within the original page size. When there are no items outside of the original page size, change the page size back to what it was before and change the view to 'fit to width'.

3. Save and republish the report, then go to your workspace and update the app.