Live course. CC:
Cannot reproduce in test course, cannot identify other courses affected by this issue.
1. View the 8.05.1x textbook: https://courses.edx.org/courses/course-v1:MITx+8.05.1x+1T2016/pdfbook/0/
2. Check out Chapter 1, see the content there
3. Click on Chapter 2, see "unexpected server response"
Expected behavior: Chapter 2, a pdf asset, would load
Actual behavior: server error