Before I claim, it disappear. It was 9 gold box reward mission for 3000 xp in halloween mission.
''Holiday mission and the special Halloween map will be removed at 02:00 UTC on November 6th, make sure you collect the rewards for the mission or they will be gone.''
More info you can find in Halloween topic on forum.
Today i have claimed my weekly reward includes 1 container and 3 weekly containers. But when checked to open them in containers menu (in HTML5), there was no container to open.
Please find the solution here. Follow the steps mentioned there, good luck!
Customer support service by UserEcho