Hi Barna, Yes, this functionality has changes, see PR #2280. Could you try whether e.retrieve_sender_node_id_from_source_table() works in this case? Thanks, Susanne ________________________________ From: Barna Zajzon &lt;b.zajzon(a)fz-juelich.de&gt; Sent: Friday, June 24, 2022 10:19 PM To: NEST User Mailing List &lt;users(a)nest-simulator.org&gt; Subject: [NEST Users] Invalid SpikeEvent variables - e.get_sender_node_id() You don't often get email from b.zajzon(a)fz-juelich.de. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification> Dear NEST community, I was wondering if there have been some changes from NEST 2.x -> 3.x regarding how the SpikeEvent variables are set and their availability in the handle(SpikeEvent& e) function. With 2.20.0, I could access the sender ID from inside the handle() function. With the current master branch, however, this is not possible anymore (or likely I'm doing it wrong). The following one-line addition to the iaf_cond_exp model (the exact model doesn't really matter): void nest::iaf_cond_exp::handle( SpikeEvent& e ) { assert( e.get_delay_steps() > 0 ); std::cout << "iaf_cond_exp >> e.get_sender_node_id(): " << e.get_sender_node_id() << std::endl << std::flush; if ( e.get_weight() > 0.0 ) ... fails with: python: /home/zbarni/software/packages/nest/znest/nestkernel/event.h:1336: nest::index nest::Event::get_sender_node_id() const: Assertion `sender_node_id_ > 0' failed. Furthermore, the SpikeEvent seems invalid (?), as the e.is_valid() call returns a 0. Is this the expected behavior, and if so, are there any alternatives to access the ID of the sender node in the handle() function? Thank you, Barna -- Barna Zajzon PhD Candidate Computation in Neural Circuits Group Institute of Neuroscience and Medicine (INM-6) Institute for Advanced Simulation (IAS-6) JARA Institute Brain Structure-Function Relationships (INM-10) Jülich Research Centre and JARA 52425 Jülich, Germany http://www.fz-juelich.de/inm/inm-6 ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------ Forschungszentrum Juelich GmbH 52425 Juelich Sitz der Gesellschaft: Juelich Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498 Vorsitzender des Aufsichtsrats: MinDir Volker Rieke Geschaeftsfuehrung: Prof. Dr.-Ing. Wolfgang Marquardt (Vorsitzender), Karsten Beneke (stellv. Vorsitzender), Prof. Dr. Astrid Lambrecht, Prof. Dr. Frauke Melchior ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------ Neugierige sind herzlich willkommen am Sonntag, den 21. August 2022, von 10:00 bis 17:00 Uhr. Mehr unter: https://www.tagderneugier.de