this is a quick overriding of the error:
The changes (three lines) are in the file
moodle/theme/boost_o365teams/renderers.php
In line 28
change
require_once($CFG->
dirroot . '/mod/assign/renderer.php');
to
require_once($CFG->dirroot . '/mod/assign/classes/output/renderer.php');
as the renderer.php was moved to another location.
In line 37 change
class theme_boost_o365teams_mod_assign_renderer extends mod_assign_renderer {
to
class theme_boost_o365teams_mod_assign_renderer extends \mod_assign\output\renderer {
And in line 44 change
public function render_assign_header(assign_header $header) {
to
public function render_assign_header(mod_assign\output\assign_header $header) {
That's all I had to make it work again.
Code source :
Daniel M github