There are some limitations on what kind of operations we can convert to MLIR. These operations are traced and almost ready to be converted to MLIR but they cannot yet. If you are getting this error when you try to compile a function, please check out our issues to see our progress on the topic. If you cannot find an issue for what you are trying to do, please create one (see Debugging / Support / Submitting Issues — Concrete Numpy Manual for further details). You can track which numpy functions can be compiled in Numpy Support — Concrete Numpy Manual.