# Error in PennyLane Lightning: an illegal memory access was encountered **URL:** \ **Category:** PennyLane Help\ **Created:** [March 15, 2025, 5:33am UTC](https://discuss.pennylane.ai/t/error-in-pennylane-lightning-an-illegal-memory-access-was-encountered/8157 "2025-03-15T05:33:20Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![QuantumMan](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/quantumman/32/2509_2.png) [@QuantumMan](https://discuss.pennylane.ai/u/QuantumMan)\ **Post date:** [March 15, 2025, 5:33am UTC](https://discuss.pennylane.ai/t/error-in-pennylane-lightning-an-illegal-memory-access-was-encountered/8157/1 "2025-03-15T05:33:20Z")
I installed pennylane-lightning gpu with mpi support on Nersc Perlmutter with modules. using instructions - [quantum-mini-apps/src/mini\_apps/quantum\_simulation/distributed\_state\_vector at main · radical-cybertools/quantum-mini-apps · GitHub](https://github.com/radical-cybertools/quantum-mini-apps/tree/main/src/mini_apps/quantum_simulation/distributed_state_vector#pennylane-lightninggpu-from-source-on-perlmutter). (kind of formulated from previous posts) It used to work, but some upgrade on the HPC causing the error. I don’t see the installation failing for any reason and could successfully install pennylane-lgpu successfully with mpi support. Hello! If applicable, put your complete code example down below. Make sure that your code: - is 100% self-contained — someone can copy-paste exactly what is here and run it to reproduce the behaviour you are observing - includes comments ```auto from mpi4py import MPI import pennylane as qml from pennylane import numpy as np from timeit import default_timer as timer import sys print("starting") comm = MPI.COMM_WORLD rank = comm.Get_rank() size = comm.Get_size() print("Initialized mpi") print(size) # Set number of runs for timing averaging num_runs = 3 # Choose number of qubits (wires) and circuit layers n_wires =int(sys.argv[1]) print(n_wires) n_layers = 2 # Instantiate CPU (lightning.qubit) or GPU (lightning.gpu) device # mpi=True to switch on distributed simulation # batch_obs=True to reduce the device memory demand for adjoint backpropagation dev = qml.device('lightning.gpu', wires=n_wires, mpi=True, batch_obs=True) # Create QNode of device and circuit @qml.qnode(dev, diff_method="adjoint") def circuit_adj(weights): qml.StronglyEntanglingLayers(weights, wires=list(range(n_wires))) return qml.math.hstack([qml.expval(qml.PauliZ(i)) for i in range(n_wires)]) # Set trainable parameters for calculating circuit Jacobian at the rank=0 process if rank == 0: params = np.random.random(qml.StronglyEntanglingLayers.shape(n_layers=n_layers, n_wires=n_wires)) else: params = None # Broadcast the trainable parameters across MPI processes from rank=0 process params = comm.bcast(params, root=0) # Run, calculate the quantum circuit Jacobian and average the timing results timing = [] for t in range(num_runs): start = timer() jac = qml.jacobian(circuit_adj)(params) end = timer() timing.append(end - start) # MPI barrier to ensure all calculations are done comm.Barrier() if rank == 0: print("num_gpus: ", size, " wires: ", n_wires, " layers ", n_layers, " time: ", qml.numpy.mean(timing)) ``` If you want help with diagnosing an error, please put the full error message below: ```auto Traceback (most recent call last): File "/global/u1/p/prmantha/dist_mem_jacobian.py", line 47, in jac = qml.jacobian(circuit_adj)(params) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/_grad.py", line 517, in _jacobian_function jac = tuple(_jacobian(func, arg)(*args, **kwargs) for arg in _argnum) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/_grad.py", line 517, in jac = tuple(_jacobian(func, arg)(*args, **kwargs) for arg in _argnum) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/autograd/wrap_util.py", line 20, in nary_f return unary_operator(unary_f, x, *nary_op_args, **nary_op_kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/autograd/differential_operators.py", line 60, in jacobian vjp, ans = _make_vjp(fun, x) ^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/autograd/core.py", line 10, in make_vjp end_value, end_node = trace(start_node, fun, x) ^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/autograd/tracer.py", line 10, in trace end_box = fun(start_box) ^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/autograd/wrap_util.py", line 15, in unary_f return fun(*subargs, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/workflow/qnode.py", line 987, in __call__ return self._impl_call(*args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/workflow/qnode.py", line 977, in _impl_call res = self._execution_component(args, kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/workflow/qnode.py", line 935, in _execution_component res = qml.execute( ^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/workflow/execution.py", line 624, in execute results = ml_boundary_execute(tapes, execute_fn, jpc, device=device) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/workflow/interfaces/autograd.py", line 147, in autograd_execute return _execute(parameters, tuple(tapes), execute_fn, jpc) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/autograd/tracer.py", line 44, in f_wrapped ans = f_wrapped(*argvals, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/autograd/tracer.py", line 48, in f_wrapped return f_raw(*args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/workflow/interfaces/autograd.py", line 183, in _execute return _to_autograd(execute_fn(tapes)) ^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/workflow/jacobian_products.py", line 464, in execute_and_cache_jacobian results, jac = self._dev_execute_and_compute_derivatives(tapes) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/workflow/jacobian_products.py", line 429, in _dev_execute_and_compute_derivatives return self._device.execute_and_compute_derivatives(numpy_tapes, self._execution_config) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/devices/modifiers/simulator_tracking.py", line 97, in execute_and_compute_derivatives return untracked_execute_and_compute_derivatives(self, circuits, execution_config) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/devices/modifiers/single_tape_support.py", line 62, in execute_and_compute_derivatives results, jacs = batch_execute_and_compute_derivatives(self, circuits, execution_config) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/devices/modifiers/simulator_tracking.py", line 97, in execute_and_compute_derivatives return untracked_execute_and_compute_derivatives(self, circuits, execution_config) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane/devices/modifiers/single_tape_support.py", line 62, in execute_and_compute_derivatives results, jacs = batch_execute_and_compute_derivatives(self, circuits, execution_config) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane_lightning/core/lightning_newAPI_base.py", line 334, in execute_and_compute_derivatives results = tuple( ^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane_lightning/core/lightning_newAPI_base.py", line 335, in self.simulate_and_jacobian( File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane_lightning/core/lightning_newAPI_base.py", line 228, in simulate_and_jacobian res = self.simulate(circuit, state) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/global/u1/p/prmantha/pennylane-lightning/pennylane_lightning/lightning_gpu/lightning_gpu.py", line 542, in simulate return self.LightningMeasurements(final_state).measure_final_state(circuit) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane_lightning/core/_measurements_base.py", line 261, in measure_final_state return tuple(self.measurement(mp) for mp in circuit.measurements) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane_lightning/core/_measurements_base.py", line 261, in return tuple(self.measurement(mp) for mp in circuit.measurements) ^^^^^^^^^^^^^^^^^^^^ File "/pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages/pennylane_lightning/core/_measurements_base.py", line 240, in measurement return self.get_measurement_function(measurementprocess)(measurementprocess) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/global/u1/p/prmantha/pennylane-lightning/pennylane_lightning/lightning_gpu/_measurements.py", line 200, in expval return self._measurement_lightning.expval( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ pennylane_lightning.lightning_gpu_ops.LightningException: [/global/u1/p/prmantha/pennylane-lightning/pennylane_lightning/core/src/simulators/lightning_gpu/StateVectorCudaMPI.hpp][Line:2208][Method:applyMPI_Dispatcher]: Error in PennyLane Lightning: an illegal memory access was encountered terminate called after throwing an instance of 'Pennylane::Util::LightningException' what(): [/global/u1/p/prmantha/pennylane-lightning/pennylane_lightning/core/src/utils/cuda_utils/DataBuffer.hpp][Line:133][Method:~DataBuffer]: Error in PennyLane Lightning: an illegal memory access was encountered srun: error: nid200321: task 0: Aborted srun: Terminating StepId=36872546.1 srun: error: nid200324: task 2: Aborted slurmstepd: error: ***STEP 36872546.1 ON nid200321 CANCELLED AT 2025-03-15T05:25:01*** srun: error: nid200321: task 1: Terminated srun: error: nid200324: task 3: Terminated srun: Force Terminated StepId=36872546.1 ``` And, finally, make sure to include the versions of your packages. Specifically, show us the output of `qml.about()`. ```auto Version: 0.39.0 Summary: PennyLane is a cross-platform Python library for quantum computing, quantum machine learning, and quantum chemistry. Train a quantum computer the same way as a neural network. Home-page: https://github.com/PennyLaneAI/pennylane Author: Author-email: License: Apache License 2.0 Location: /pscratch/sd/p/prmantha/lgpu_env/lib/python3.11/site-packages Requires: appdirs, autograd, autoray, cachetools, networkx, numpy, packaging, pennylane-lightning, requests, rustworkx, scipy, toml, typing-extensions Required-by: PennyLane_Lightning, PennyLane_Lightning_GPU Platform info: Linux-5.14.21-150500.55.65_13.0.73-cray_shasta_c-x86_64-with-glibc2.31 Python version: 3.11.7 Numpy version: 2.0.2 Scipy version: 1.15.2 Installed devices: - lightning.gpu (PennyLane_Lightning_GPU-0.39.0) - lightning.qubit (PennyLane_Lightning-0.39.0) - default.clifford (PennyLane-0.39.0) - default.gaussian (PennyLane-0.39.0) - default.mixed (PennyLane-0.39.0) - default.qubit (PennyLane-0.39.0) - default.qutrit (PennyLane-0.39.0) - default.qutrit.mixed (PennyLane-0.39.0) - default.tensor (PennyLane-0.39.0) - null.qubit (PennyLane-0.39.0) - reference.qubit (PennyLane-0.39.0) >>> ``` ---
**Author:** ![CatalinaAlbornoz](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/catalinaalbornoz/32/1196_2.png) [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Post date:** [March 17, 2025, 9:14pm UTC](https://discuss.pennylane.ai/t/error-in-pennylane-lightning-an-illegal-memory-access-was-encountered/8157/2 "2025-03-17T21:14:02Z")
Hi @QuantumMan , Are you able to upgrade to the latest PennyLane version (PennyLane v0.40) and let us know if you’re still experiencing this issue? ---
**Author:** ![QuantumMan](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/quantumman/32/2509_2.png) [@QuantumMan](https://discuss.pennylane.ai/u/QuantumMan)\ **Post date:** [March 18, 2025, 1:01am UTC](https://discuss.pennylane.ai/t/error-in-pennylane-lightning-an-illegal-memory-access-was-encountered/8157/3 "2025-03-18T01:01:19Z")
Yes, i tried v0.40 and still same issue - i think with some latest version of NERSC HPC upgrade, this is broken now. @mlxd helped before with similar issues. But pennylane lightning gpu build should catch it. Now i am not sure where to look for. File “/global/u1/p/prmantha/pennylane-lightning/pennylane\_lightning/lightning\_gpu/lightning\_gpu.py”, line 464, in simulate return self.LightningMeasurements(final\_state).measure\_final\_state(circuit) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File “/pscratch/sd/p/prmantha/lgpu\_env/lib/python3.11/site-packages/pennylane\_lightning/core/\_measurements\_base.py”, line 261, in measure\_final\_state return tuple(self.measurement(mp) for mp in circuit.measurements) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File “/pscratch/sd/p/prmantha/lgpu\_env/lib/python3.11/site-packages/pennylane\_lightning/core/\_measurements\_base.py”, line 261, in return tuple(self.measurement(mp) for mp in circuit.measurements) ^^^^^^^^^^^^^^^^^^^^ File “/pscratch/sd/p/prmantha/lgpu\_env/lib/python3.11/site-packages/pennylane\_lightning/core/\_measurements\_base.py”, line 240, in measurement return self.get\_measurement\_function(measurementprocess)(measurementprocess) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File “/global/u1/p/prmantha/pennylane-lightning/pennylane\_lightning/lightning\_gpu/\_measurements.py”, line 196, in expval return self.\_measurement\_lightning.expval( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ pennylane\_lightning.lightning\_gpu\_ops.LightningException: [/global/u1/p/prmantha/pennylane-lightning/pennylane\_lightning/core/src/simulators/lightning\_gpu/StateVectorCudaMPI.hpp][Line:2187][Method:applyMPI\_Dispatcher]: Error in PennyLane Lightning: an illegal memory access was encountered terminate called after throwing an instance of ‘Pennylane::Util::LightningException’ what(): [/global/u1/p/prmantha/pennylane-lightning/pennylane\_lightning/core/src/utils/cuda\_utils/DataBuffer.hpp][Line:133][Method:~DataBuffer]: Error in PennyLane Lightning: an illegal memory access was encountered srun: error: nid200412: task 2: Aborted srun: Terminating StepId=36968770.1 slurmstepd: error: \*\*\* STEP 36968770.1 ON nid200409 CANCELLED AT 2025-03-18T00:59:23 \*\*\* srun: error: nid200409: task 0: Aborted ---
**Author:** ![QuantumMan](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/quantumman/32/2509_2.png) [@QuantumMan](https://discuss.pennylane.ai/u/QuantumMan)\ **Post date:** [March 18, 2025, 1:01am UTC](https://discuss.pennylane.ai/t/error-in-pennylane-lightning-an-illegal-memory-access-was-encountered/8157/4 "2025-03-18T01:01:57Z")
17:59:25 (lgpu\_env) prmantha@nid200409:~ $ python Python 3.11.7 | packaged by conda-forge | (main, Dec 23 2023, 14:43:09) [GCC 12.3.0] on linux Type “help”, “copyright”, “credits” or “license” for more information. > > > import pennylane as qml > > > qml.ab\>\>\> qml.about() > > > Name: PennyLane > > > Version: 0.40.0 > > > Summary: PennyLane is a cross-platform Python library for quantum computing, quantum machine learning, and quantum chemistry. Train a quantum computer the same way as a neural network. > > > Home-page: [GitHub - PennyLaneAI/pennylane: PennyLane is a cross-platform Python library for quantum computing, quantum machine learning, and quantum chemistry. Train a quantum computer the same way as a neural network.](https://github.com/PennyLaneAI/pennylane) > > > Author: > > > Author-email: > > > License: Apache License 2.0 > > > Location: /pscratch/sd/p/prmantha/lgpu\_env/lib/python3.11/site-packages > > > Requires: appdirs, autograd, autoray, cachetools, diastatic-malt, networkx, numpy, packaging, pennylane-lightning, requests, rustworkx, scipy, tomlkit, typing-extensions > > > Required-by: PennyLane\_Lightning, PennyLane\_Lightning\_GPU Platform info: Linux-5.14.21-150500.55.65\_13.0.73-cray\_shasta\_c-x86\_64-with-glibc2.31 Python version: 3.11.7 Numpy version: 2.0.2 Scipy version: 1.15.2 Installed devices: - lightning.qubit (PennyLane\_Lightning-0.40.0) - lightning.gpu (PennyLane\_Lightning\_GPU-0.40.0) - default.clifford (PennyLane-0.40.0) - default.gaussian (PennyLane-0.40.0) - default.mixed (PennyLane-0.40.0) - default.qubit (PennyLane-0.40.0) - default.qutrit (PennyLane-0.40.0) - default.qutrit.mixed (PennyLane-0.40.0) - default.tensor (PennyLane-0.40.0) - null.qubit (PennyLane-0.40.0) - reference.qubit (PennyLane-0.40.0) > > > ---
**Author:** ![CatalinaAlbornoz](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/catalinaalbornoz/32/1196_2.png) [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Post date:** [March 18, 2025, 7:03pm UTC](https://discuss.pennylane.ai/t/error-in-pennylane-lightning-an-illegal-memory-access-was-encountered/8157/5 "2025-03-18T19:03:40Z")
Thanks for reporting this @QuantumMan . We’re investigating and will get back to you with more info. ---
**Author:** ![CatalinaAlbornoz](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/catalinaalbornoz/32/1196_2.png) [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Post date:** [March 19, 2025, 8:43pm UTC](https://discuss.pennylane.ai/t/error-in-pennylane-lightning-an-illegal-memory-access-was-encountered/8157/6 "2025-03-19T20:43:20Z")
Hi @QuantumMan , Our team suspects that this could be due to some combination of CUDA library changes and Cray MPICH changes. Something you can try is downgrading your CUDA + Cray MPICH version (the system should allow module loading of old versions). Unfortunately we can’t perform tests on this system so we can’t really know what versions will work. Let us know if you can downgrade to versions that work again. It might help others too. ---
**Author:** ![Enrique](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/enrique/32/4442_2.png) [@Enrique](https://discuss.pennylane.ai/u/Enrique)\ **Post date:** [September 20, 2026, 2:51am UTC](https://discuss.pennylane.ai/t/error-in-pennylane-lightning-an-illegal-memory-access-was-encountered/8157/7 "2026-09-20T02:51:49Z")
Hey @QuantumMan, same error here on Perlmutter with lightning.gpu + MPI for Jacobian. I ran into this after the cuda stack update too. In my case it was the MPI dispatcher hitting the memory ceiling on simulate\_and\_jacobian - not your install. I have a private solver that runs that same workload locally without the illegal access error, even for large sizes. Happy to run your circuit\_adj case privately as a test and send you back the jacobian value if you want to compare. Just DM the wires/params count. No need to post your full code here. ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex012/uploads/pennylane/original/2X/e/e64663b1e0ef3b714a28f626004164f29dc41364.png) [@system](https://discuss.pennylane.ai/u/system)\ **Post date:** [September 20, 2026, 2:51am UTC](https://discuss.pennylane.ai/t/error-in-pennylane-lightning-an-illegal-memory-access-was-encountered/8157/8 "2026-09-20T02:51:52Z")
This topic is temporarily closed for at least 1 hour due to a large number of community flags. ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex012/uploads/pennylane/original/2X/e/e64663b1e0ef3b714a28f626004164f29dc41364.png) [@system](https://discuss.pennylane.ai/u/system)\ **Post date:** [September 28, 2026, 9:46pm UTC](https://discuss.pennylane.ai/t/error-in-pennylane-lightning-an-illegal-memory-access-was-encountered/8157/9 "2026-09-28T21:46:19Z")
This topic was automatically opened after 8 days.