bad marshal data (unknown type code)

[jmaldon1]

with open("./Models/gen.json", "r") as json_file:
    model_json = json_file.read()
model = model_from_json(model_json, custom_objects={"Conv2DMod": Conv2DMod})
model.load_weights("./Models/gen_19.h5")

ValueError: bad marshal data (unknown type code)

I get this error when trying to load pretrained model gen.json and genMA.json.

Versions:
tensorflow = "2.2.3"
tf.keras.__version__ == 2.3.0-tf

Also tried higher version of tensorflow like 2.5.0 and still did not work.