Python opencv error ('cv::cvtcolor')

<pre>img_file = 'test2.png'

img = cv2.imread(img_file, 1)
img = cv2.cvtColor(img,cv2.COLOR_BGR2RGB)
print(f"Loaded {img_file} ({img.shape[1]} x {img.shape[0]})" )

# Resize if image larger than 2k pixels on a side
if img.shape[1] > 2000 or img.shape[0] > 2000:
    print(f"Image too big ({img.shape[1]} x {img.shape[0]})")
    new_size = 800.0 # px
    if img.shape[1] > img.shape[0]:
        # resize by width to new limit
        ratio = new_size / img.shape[1]
        
    else:
        # resize by height
        ratio = new_size / img.shape[0]
    print(f"Reducing by factor of {(1./ratio)}" )
#     img = cv2.resize(img,(0,0),fx=ratio,fy=ratio)
    print (f"New size: ({img.shape[1]} x {img.shape[0]})")

# See original image
plt.imshow(np.asarray(img))

error: OpenCV(4.5.3) C:\Users\runneradmin\AppData\Local\Temp\pip-req-build-sn_xpupm\opencv\modules\imgproc\src\color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'

<pre>---------------------------------------------------------------------------
error                                     Traceback (most recent call last)
~\AppData\Local\Temp/ipykernel_7268/4163631807.py in <module>
      2 
      3 img = cv2.imread(img_file, 1)
----> 4 img = cv2.cvtColor(img,cv2.COLOR_BGR2RGB)
      5 print(f"Loaded {img_file} ({img.shape[1]} x {img.shape[0]})" )
      6 

img = cv2.imread(img_file, 1)

img = cv2.imread(img_file)