I tried using any of the Timm convnext encoders with UNetPlusPlus, and always get the following runtime error: Given groups=1, expected weight to be at least 1 at dimension 0, but got weight of size [0,96,3,3] . (The 96 part changes depending on what size the encoder is). I believe this has to do with how theDecoderBlock out_channels are initialized. I poked around a bit and think this has to do with a difference in how encoder levels are generally initialized in backbones like ResNet/EffNet vstimm_encoder. If initialized with an encoder of depth 2, the problem disappears, but deeper Us have the problem.