Hi bro you should not use the textures name "Mat_Frozenfood", You should use the format like this "UID.Material_name.channel.liner(or)srgb based on the channel.1001"
For Eg:-
XXX_XXXX_XXXX_XXXXX_XXXX_XXX.plastic_stainremover.ambient_occlusion.linear.1001
XXX_XXXX_XXXX_XXXXX_XXXX_XXX.plastic_stainremover.base_color.srgb.1001 (srgb only for basecolor) & No capital letters , everything should be in small, even if you miss a space that also will give this error.
Hope this helps!