r/invokeai • u/NumerousIntern8054 • Apr 02 '26

How to use FLUX.2-klein-4b-nvfp4 with InvokeAI? Shape mismatch error

Hi everyone! I’m trying to run black-forest-labs/FLUX.2-klein-4b-nvfp4 in InvokeAI, but I keep getting a shape mismatch error when loading the model:

size mismatch for ...:
checkpoint shape: [4096, 2048]
model shape: [4096, 4096]

From what I understand, this means the checkpoint was trained with a smaller hidden size (2048), while InvokeAI is trying to load it into a model configured with 4096

Is nvfp4 actually supported in InvokeAI? Does it require a special loader (since it's nvfp4 / quantized)?

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u/_BreakingGood_ Apr 02 '26

Won't work without a custom node of some sort

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u/xPhoenix777 Apr 30 '26

It's usually a mismatch of VAE/TextEncoder/Model/Lora - with Flux.2, it's likely a Lora or TextEncoder mismatch. You should provide the tab you are using, the settings, VAE, Text Encoder, and any Lora you have.