Hello, I have followed the exact same steps as shown in this video: https://www.youtube.com/watch?v=M9ntwQie9vs to create a custom RFNoC Gain block. I successfully built the FPGA bitstream and booted the E310 device with it. After flashing, I confirmed that the RFNoC blocks were correctly loaded. The output is: RFNoC blocks on this device: * 0/Gain#0 * 0/Radio#0 Static connections on this device: * 0/SEP#0:0 ==> 0/Radio#0:0 * 0/Radio#0:0 ==> 0/SEP#0:0 * 0/SEP#1:0 ==> 0/Radio#0:1 * 0/Radio#0:1 ==> 0/SEP#1:0 * 0/SEP#2:0 ==> 0/Gain#0:0 * 0/Gain#0:0 ==> 0/SEP#2:0 In addition to generating the bitstream, I also created and included the required .yml files — specifically the block descriptor (gain.yml) and image core (e310_rfnoc_image_core.yml). I confirmed that the image builder detects them successfully when using --log-level debug. However, when I try to recreate the block diagram in GNU Radio Companion, following the same structure as shown in the video, I encounter the following error during Python code generation: Generating: "/home/aufer/Projects/rfnoc-gain/rfnoc_gain_trial.py" Generate Error: Undefined >>> Failure Traceback (most recent call last): File "/home/aufer/gnuradio-install/lib/python3.12/site-packages/gnuradio/grc/gui/Application.py", line 758, in _handle_action generator.write() File "/home/aufer/gnuradio-install/lib/python3.12/site-packages/gnuradio/grc/core/generator/top_block.py", line 86, in write for filename, data in self._build_python_code_from_template(): ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/aufer/gnuradio-install/lib/python3.12/site-packages/gnuradio/grc/core/generator/top_block.py", line 135, in _build_python_code_from_template connections=self._connections(), ^^^^^^^^^^^^^^^^^^^ File "/home/aufer/gnuradio-install/lib/python3.12/site-packages/gnuradio/grc/core/generator/top_block.py", line 328, in _connections code = template.render( ^^^^^^^^^^^^^^^^ File "/usr/lib/python3/dist-packages/mako/template.py", line 438, in render return runtime._render(self, self.callable_, args, data) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/lib/python3/dist-packages/mako/runtime.py", line 874, in _render _render_context( File "/usr/lib/python3/dist-packages/mako/runtime.py", line 916, in _render_context _exec_template(inherit, lclcontext, args=args, kwargs=kwargs) File "/usr/lib/python3/dist-packages/mako/runtime.py", line 943, in _exec_template callable_(context, *args, **kwargs) File "memory:0x77b7681a8ce0", line 32, in render_body File "/usr/lib/python3/dist-packages/mako/runtime.py", line 230, in __str__ raise NameError("Undefined") NameError: Undefined This occurs when GRC attempts to generate the .py file. Could you please advise what might be missing or misconfigured to cause this “Undefined” error? Best regards,