Error only occurs when scipy.minimize is L-BFGS-B

import scope.optimize as opt

bound=opt.Bounds(#np.ndarray, #np.ndarray)
result=opt.minimize(loss_f,x0_ft,method='L-BFGS-B',jac=f_grad, 
              bound=bound, toll=10e-6, options={'maxiter':100, 'disp':True})

RUNNING THE L-BFGS-BCODE

           * * *

Machine precision = 2.220D-16
 N = 9 M = 10

At X00 variables are exactly at the boundes
# Standard output up to this point

# Error output from here
Traceback (most recent call last):
  File "main.py", line 147, in<module>
    main()
  File "main.py", line 120, in main
    options={'maxiter':100, 'disp':True})
  File "Abbreviated /scipy/optimize/_minimize.py", line 600, in minimize
    callback=callback,**options)
  File "Abbreviated /scipy/optimize/lbfgsb.py", line328, in_minimize_lbfgsb
    isave, dsave, maxls)
ValueError: failed to initialize int(inout) array --expected elsize=8 but got4