New Delhi, Aug. 2 -- Ten days before its first online open-book exam (OBE), Delhi University on Saturday began the second phase of mock tests for final-year students.

The first phase of mock tests conducted between July 27 and 29 consisted of generic questions while those that began on Saturday, and will continue till August 4, were "based on real version and single paper of each program of final semester/year of undergraduate and postgraduate programmes of the current batch".

Students took to social media on Saturday to complain of issues they faced during the papers.

"I was previewing my answers and when I opened the second file, someone else's file was showing," tweeted a final-year student of Faculty of Law, Delhi University.