You can find a file 'conversation.txt' in your %mount and blade%\Module\Native, where %mount and blade% is "C:\Program Files\Mount&Blade" in general, or "C:\Program Files\Steam\steamapps\common\mount and blade\Modules\Native" in steam version.
1. Find a row with 'dlga_event_triggered:rebel_thanks_answer'.
2. You can see {s6} in the row. Replace the {s6} with {playername},_when_we_started_our_long_walk,_few_people_had_the_courage_to_support_me._And_fewer_still_would_be_willing_to_put_their_lives_at_risk_for_my_cause._But_you_didn't_hesitate_for_a_moment_in_throwing_yourself_at_my_enemies._We_have_gone_through_a_lot_together,_and_there_were_times_I_came_close_to_losing_all_hope._But_with_God's_help,_we_prevailed._It_is_now_time_for_me_to_leave_your_company_and_take_what's_rightfully_mine._From_now_on,_I_will_carry_out_the_great_responsibility_of_ruling_{s3}._There_still_lie_many_challanges_ahead_and_I_count_on_your_help_in_overcoming_those._And_of_course,_you_will_always_remain_as_my_foremost_vassal.
At least, the problem related to 'NO STRING' will be fixed, and you can quit the rebel quest successfully.Still, a few of bugs remain related to rebellion. For example, if you serve the king(pretender) after his/her rebellion was already finished, the rebellion quest will be restarted and the faction will be against you.
