Mav_cmd_component_arm_disarm command temporarily rejected

Hi, i’m using QGC to control my pixhawk 2.4.8. i got a trouble “mav_cmd_component_arm_disarm command temporarily rejected”. My firmware is 1.14.0beta. How can i solve this problem?
By the way, Is it possible to take off without GPS? I can’t take off without GPS!
Thanks a lot

Check this param regarding arming without GPS: