I recently upgrade to Moodle 2.9 but when the students want to access their profiles have the below message
Debug info:
Error code: codingerror
Stack trace:

line 62 of \user\classes\output\myprofile\tree.php: coding_exception thrown
line 380 of \lib\myprofilelib.php: call to core_user\output\myprofile\tree->add_node()
line 53 of \user\classes\output\myprofile\manager.php: call to core_myprofile_navigation()
line 220 of \user\profile.php: call to core_user\output\myprofile\manager::build_tree()