Invalid Trajectory: start point deviates from current robot state more than 0.01 joint

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Hello,everyone:

I am working on a programme which aims at using the EMG signals to control the robot.I have finished a version of script.I use the execute(plan,False) to async execute the path. When I stop the robot use MoveGroupCommander.stop() ,I compute a new cartesian path like this

    arm.stop()
    start_pose = arm.get_current_pose(end_effector_link).pose
    if (start_pose.position.z>0)or(start_pose.position.z==0):
        theta=math.acos((start_pose.position.x-0.5)*4)
else:
    theta=(math.acos((start_pose.position.x-0.5)*4))*(-1)
delta=(theta-math.pi*1/2)/32
#rospy.loginfo(theta)
    waypoints = []
    wpose=[]

    if cartesian:
        waypoints.append(start_pose)


    wpose = deepcopy(start_pose)#
    for i in range(30):
        wpose.position.x = 0.5+math.cos(theta)*0.25
        wpose.position.z = math.sin(theta)*0.25
        if cartesian:  
            waypoints.append(deepcopy(wpose))
        theta -=delta

#rospy.loginfo(theta)
    if cartesian:
        fraction = 0.0   
        maxtries = 100  
        attempts = 0     


        arm.set_start_state_to_current_state()


        while fraction < 1.0 and attempts < maxtries:

            (plan, fraction) = arm.compute_cartesian_path (
                                    waypoints,   # waypoint poses，
                                    0.001,        # eef_step，
                                    0.0,         # jump_threshold
                                    True)        # avoid_collisions


            attempts += 1


            if attempts % 10 == 0:
                rospy.loginfo("Still trying after " + str(attempts) + " attempts...")


        if fraction == 1.0:
            rospy.loginfo("Path computed successfully. Moving the arm.")
            arm.execute(plan,False)
            rospy.loginfo("Path execution complete.")

        else:
            rospy.loginfo("Path planning failed with only " + str(fraction) + " success after " + str(maxtries) + " attempts.")

but the terminal report error:"Invalid Trajectory: start point deviates from current robot state more than 0.01 joint"

I wonder why this error occurs because I have set the current pose to the start pose.

Thanks for your reading and I will appreciate if anyone give me some advice