How do i fix the error: ValueError: too many values to unpack (expected 2)

Question

The code is as follows:

from astropy.io import fits

import matplotlib
import matplotlib.pyplot as plt
import numpy as np

hdu = fits.open('1/img/r1464838.fit')
hdu[1].header
img = hdu[1].data
print(img.shape)

hdu1 = fits.open('MCtest_C1.fits')
coeff=hdu1


for i in range(1024):
    for j in range(1024):
        nonlin = coeff[0,i,j]*img**3 + coeff[1,i,j]*img**2 + coeff[2,i,j]*img**1 + coeff[3,i,j]*img**0 
        print(nonlin)
        corrected_img = (filelist)/nonlin

The issue appears to arise on the nonlin line. Not too sure how to go about fixing this problem.

Any help would be great.

Thanks!