When I change the role to "Student" to view the lesson, there is the error message as following.

Error: could not find lesson_timer records

Debug info:

Error code: cannotfindtimer

Stack trace: •line 476 of \lib\setuplib.php: moodle_exception thrown
•line 1219 of \mod\lesson\locallib.php: call to print_error()
•line 297 of \mod\lesson\view.php: call to lesson->update_timer()

I have search on the moodle and find one article:
https://moodle.org/mod/forum/discuss.php?d=165375
and read the links in it. But the links are in 2007 and the codes are very different in the version I used: v2.2.10

I have reproduced the error in v2.5 and the error is the same.

Thank you in advance!