# Errors **URL:** https://fenicsproject.discourse.group/c/errors/13.md [Latest](https://fenicsproject.discourse.group/latest.md) · [Categories](https://fenicsproject.discourse.group/categories.md) · [Tags](https://fenicsproject.discourse.group/tags.md) --- ## [About the Errors category](https://fenicsproject.discourse.group/t/about-the-errors-category/5818)
**Author:** [@jackhale](https://fenicsproject.discourse.group/u/jackhale)\ **Replies:** 0
This category should be used when an issue results in a runtime error, e.g. syntax error, function being called with wrong arguments (argument error), or a crash. --- ## [Mesh cannot run due to TypeError](https://fenicsproject.discourse.group/t/mesh-cannot-run-due-to-typeerror/19605)
**Author:** [@yjin6](https://fenicsproject.discourse.group/u/yjin6)\ **Replies:** 4\ **Last updated:** [March 19, 2026, 1:39am UTC](https://fenicsproject.discourse.group/t/mesh-cannot-run-due-to-typeerror/19605 "2026-03-19T01:39:10Z")
Dear all, my dolfinx.mesh cannot work even for the simplest unit interval mesh generation. Here is the code: from mpi4py import MPI import numpy as np import ufl from dolfinx import mesh comm = MPI.COMM\_WORLD nx … --- ## [Error rendering output item using 'jupyter-ipywidget-renderer'](https://fenicsproject.discourse.group/t/error-rendering-output-item-using-jupyter-ipywidget-renderer/19590)
**Author:** [@bacig](https://fenicsproject.discourse.group/u/bacig)\ **Replies:** 2\ **Last updated:** [March 10, 2026, 3:02pm UTC](https://fenicsproject.discourse.group/t/error-rendering-output-item-using-jupyter-ipywidget-renderer/19590 "2026-03-10T15:02:53Z")
Hello! I am a beginner user of Fenicsx software and I am having problems. I installed the program through Docker, and the Python version is 3.12.3. I am using it through VS Code, as shown in Anton Evdokimov’s video (Fast… --- ## [3D Patient Specific](https://fenicsproject.discourse.group/t/3d-patient-specific/19483)
**Author:** [@mhadidy](https://fenicsproject.discourse.group/u/mhadidy)\ **Replies:** 2\ **Last updated:** [February 11, 2026, 4:48pm UTC](https://fenicsproject.discourse.group/t/3d-patient-specific/19483 "2026-02-11T16:48:17Z")
I have this geometry which is a patient specific artery with one inlet and two outlets. I’m trying to run 3D steady Navier stocks to get velocity, I tried to thing one of them is the following nonlinear forum, and also… --- ## [Code works fine on personal PC but fails on cluster installation](https://fenicsproject.discourse.group/t/code-works-fine-on-personal-pc-but-fails-on-cluster-installation/19428)
**Author:** [@Babs](https://fenicsproject.discourse.group/u/Babs)\ **Replies:** 13\ **Last updated:** [February 4, 2026, 11:06am UTC](https://fenicsproject.discourse.group/t/code-works-fine-on-personal-pc-but-fails-on-cluster-installation/19428 "2026-02-04T11:06:31Z")
Good morning everybody, I am encountering an issue with my FEniCS 2019.1.0 code on a cluster. I’ve implemented a time-dependent problem that works correctly both in serial and parallel on my personal PC with the FeniCS … --- ## [Incompatible function arguments](https://fenicsproject.discourse.group/t/incompatible-function-arguments/19355)
**Author:** [@buggyfenics](https://fenicsproject.discourse.group/u/buggyfenics)\ **Replies:** 6\ **Last updated:** [January 16, 2026, 4:13pm UTC](https://fenicsproject.discourse.group/t/incompatible-function-arguments/19355 "2026-01-16T16:13:17Z")
I am trying to port the NewFrac linear elasticity code to a modern version of Fenics. I get this error: Traceback (most recent call last): File "/usr/lib/petsc/lib/python3/dist-packages/dolfinx/fem/bcs.py", line 230, … --- ## [Segmentation fault while running on parallel cores](https://fenicsproject.discourse.group/t/segmentation-fault-while-running-on-parallel-cores/18329)
**Author:** [@nika](https://fenicsproject.discourse.group/u/nika)\ **Replies:** 1\ **Last updated:** [November 1, 2025, 6:50pm UTC](https://fenicsproject.discourse.group/t/segmentation-fault-while-running-on-parallel-cores/18329 "2025-11-01T18:50:05Z")
Hello, I am trying to run a simulation with a nonlinear variational problem using fenics 2019.1.0 on parallel cores. Using superlu\_dist linear solver I get segmentation fault after two or three iterations. I could not pi… --- ## [Help understanding correct equation form in complex mode](https://fenicsproject.discourse.group/t/help-understanding-correct-equation-form-in-complex-mode/18273)
**Author:** [@kdr](https://fenicsproject.discourse.group/u/kdr)\ **Replies:** 1\ **Last updated:** [October 17, 2025, 7:12am UTC](https://fenicsproject.discourse.group/t/help-understanding-correct-equation-form-in-complex-mode/18273 "2025-10-17T07:12:56Z")
I am a bit confused on which functions are not compatible (and how to modify them) for dolfinx complex mode. In below example, all 3 versions work for real mode, but only version 3 works for complex mode. I would like to… --- ## [2D buoyancy-driven flow (Boussinesq) through inlet patch at the top wall with circular obstacle in the room](https://fenicsproject.discourse.group/t/2d-buoyancy-driven-flow-boussinesq-through-inlet-patch-at-the-top-wall-with-circular-obstacle-in-the-room/18210)
**Author:** [@Abrar\_Nhavakar](https://fenicsproject.discourse.group/u/Abrar_Nhavakar)\ **Replies:** 3\ **Last updated:** [September 15, 2025, 1:21pm UTC](https://fenicsproject.discourse.group/t/2d-buoyancy-driven-flow-boussinesq-through-inlet-patch-at-the-top-wall-with-circular-obstacle-in-the-room/18210 "2025-09-15T13:21:28Z")
from fenics import \* import numpy as np ------------------------- Parameters ------------------------- rho = 1.0 # density mu = 0.01 # viscosity kappa = 0.01 # thermal diffusivity beta = 0.01 … --- ## [Error: libgl1 -mesa -glx-xvfb](https://fenicsproject.discourse.group/t/error-libgl1-mesa-glx-xvfb/16630)
**Author:** [@Yaser\_Seif](https://fenicsproject.discourse.group/u/Yaser_Seif)\ **Replies:** 7\ **Last updated:** [August 27, 2025, 2:52pm UTC](https://fenicsproject.discourse.group/t/error-libgl1-mesa-glx-xvfb/16630 "2025-08-27T14:52:42Z")
strong text Please Help me to handle this error. I am beginner in python and Fenicsx. I have ubuntu and anaconda navigator. when run this code from fenics tutorial this error occur. --- ## [Applying Lifting operation using PETSc](https://fenicsproject.discourse.group/t/applying-lifting-operation-using-petsc/18071)
**Author:** [@jhasbani](https://fenicsproject.discourse.group/u/jhasbani)\ **Replies:** 4\ **Last updated:** [August 6, 2025, 7:59pm UTC](https://fenicsproject.discourse.group/t/applying-lifting-operation-using-petsc/18071 "2025-08-06T19:59:48Z")
Hi everyone! I am following the beam example using PETSc interface for solving a deflection of a beam posted here: I am using FenicsX v0.9 and I am encountering a problem in the following lines from the example: g = … --- ## [Dirichletbc incompatible arguments: needs a float32 functionspace?](https://fenicsproject.discourse.group/t/dirichletbc-incompatible-arguments-needs-a-float32-functionspace/18077)
**Author:** [@AnfoDao](https://fenicsproject.discourse.group/u/AnfoDao)\ **Replies:** 2\ **Last updated:** [August 6, 2025, 2:17pm UTC](https://fenicsproject.discourse.group/t/dirichletbc-incompatible-arguments-needs-a-float32-functionspace/18077 "2025-08-06T14:17:55Z")
Hi there, I have been trying to move my fenics code to dolfinx, but have run into an issue with my Dirichlet boundary conditions. Looking at the documentation, the arguments and process have changed, but I’m not sure ho… --- ## [Looks like a package broke the solver](https://fenicsproject.discourse.group/t/looks-like-a-package-broke-the-solver/18023)
**Author:** [@fea](https://fenicsproject.discourse.group/u/fea)\ **Replies:** 6\ **Last updated:** [August 1, 2025, 6:41am UTC](https://fenicsproject.discourse.group/t/looks-like-a-package-broke-the-solver/18023 "2025-08-01T06:41:57Z")
I installed cartopy (a Python package used for creating projections of data onto Earth), and now all of my programs break at the last step when running problem.solve() with the error ------------------------------------… --- ## [Parallel run gives different output for cell to vertex for ghost elements](https://fenicsproject.discourse.group/t/parallel-run-gives-different-output-for-cell-to-vertex-for-ghost-elements/17895)
**Author:** [@Amit](https://fenicsproject.discourse.group/u/Amit)\ **Replies:** 3\ **Last updated:** [July 5, 2025, 4:38pm UTC](https://fenicsproject.discourse.group/t/parallel-run-gives-different-output-for-cell-to-vertex-for-ghost-elements/17895 "2025-07-05T16:38:00Z")
Hello! Cell to vertex mapping using domain.topology.connectivity(dim, 0) gives different output from domain.geometry.dofmap. Here is my code below: from dolfinx import mesh, fem, la import numpy as np import ufl from m… --- ## [Error while trying to run finite strain FeFp plasticity tutorial](https://fenicsproject.discourse.group/t/error-while-trying-to-run-finite-strain-fefp-plasticity-tutorial/17858)
**Author:** [@M\_Saad](https://fenicsproject.discourse.group/u/M_Saad)\ **Replies:** 1\ **Last updated:** [July 2, 2025, 9:41am UTC](https://fenicsproject.discourse.group/t/error-while-trying-to-run-finite-strain-fefp-plasticity-tutorial/17858 "2025-07-02T09:41:19Z")
Hi! I am trying to run the finite strain FeFp plasticity tutorial, but I am getting some errors while running the script. I have installed FEniCSx (v.0.8) and Jax(v.0.5.2) using conda-forge. JaxStackTraceBeforeTransform… --- ## [Error creating forms from ufl.extract\_blocks](https://fenicsproject.discourse.group/t/error-creating-forms-from-ufl-extract-blocks/17840)
**Author:** [@JuanJoZP](https://fenicsproject.discourse.group/u/JuanJoZP)\ **Replies:** 1\ **Last updated:** [June 25, 2025, 10:01pm UTC](https://fenicsproject.discourse.group/t/error-creating-forms-from-ufl-extract-blocks/17840 "2025-06-25T22:01:28Z")
Hi. Im using dolfinx version 0.9.0 on a docker container, trying to compile the forms for the block system arising from the navier-stokes equations results in an unexpected error. Here is the MWE: from petsc4py import… --- ## [Fatal error in internal\_Finalize](https://fenicsproject.discourse.group/t/fatal-error-in-internal-finalize/17783)
**Author:** [@tweng](https://fenicsproject.discourse.group/u/tweng)\ **Replies:** 5\ **Last updated:** [June 25, 2025, 4:25am UTC](https://fenicsproject.discourse.group/t/fatal-error-in-internal-finalize/17783 "2025-06-25T04:25:15Z")
Hi FEniCS community, I have encountered this problem for a bit, and I haven’t figured out what is happening. So I ran python3 myscript.py in the terminal, after the problem is solved, the program does not terminate and … --- ## [Assertion error on integrating over parts of the surface](https://fenicsproject.discourse.group/t/assertion-error-on-integrating-over-parts-of-the-surface/17705)
**Author:** [@tomd](https://fenicsproject.discourse.group/u/tomd)\ **Replies:** 2\ **Last updated:** [June 5, 2025, 4:11pm UTC](https://fenicsproject.discourse.group/t/assertion-error-on-integrating-over-parts-of-the-surface/17705 "2025-06-05T16:11:08Z")
Hi all, I am trying to include a term to the weak form that involved integrating over parts of the domain surface. After some headaches with the actual problem, I boiled down the error to this MWE (slightly obscuring th… --- ## [Error in JIT compilation of dolfinx fem forms after updating to MacOS 15.4](https://fenicsproject.discourse.group/t/error-in-jit-compilation-of-dolfinx-fem-forms-after-updating-to-macos-15-4/17376)
**Author:** [@MorenoMiguelES](https://fenicsproject.discourse.group/u/MorenoMiguelES)\ **Replies:** 2\ **Last updated:** [May 30, 2025, 2:38am UTC](https://fenicsproject.discourse.group/t/error-in-jit-compilation-of-dolfinx-fem-forms-after-updating-to-macos-15-4/17376 "2025-05-30T02:38:58Z")
Hello community, I use FEniCSx v0.9.0 with Python 3.12.2, along with scifem and other standard libraries, on a Mac M1. After updating MacOS to version 15.4 (previously 15.3), I was surprised to encounter the following … --- ## [Accessing the divergence of the vector field](https://fenicsproject.discourse.group/t/accessing-the-divergence-of-the-vector-field/17599)
**Author:** [@dries](https://fenicsproject.discourse.group/u/dries)\ **Replies:** 1\ **Last updated:** [May 12, 2025, 2:01pm UTC](https://fenicsproject.discourse.group/t/accessing-the-divergence-of-the-vector-field/17599 "2025-05-12T14:01:22Z")
I can acces the scalar field pnew but I cannot access the divergence of the vector field unew by the following code. pnew.vector()\[i\] (div(unew)).vector()\[i\] First one works but the second one doesn’t. I get the follow… --- ## [Getting error while I am trying to solve my topology optimization problem in 3d](https://fenicsproject.discourse.group/t/getting-error-while-i-am-trying-to-solve-my-topology-optimization-problem-in-3d/17502)
**Author:** [@Harsha](https://fenicsproject.discourse.group/u/Harsha)\ **Replies:** 1\ **Last updated:** [April 24, 2025, 8:14pm UTC](https://fenicsproject.discourse.group/t/getting-error-while-i-am-trying-to-solve-my-topology-optimization-problem-in-3d/17502 "2025-04-24T20:14:51Z")
getting an error while I am trying to solve my topology optimization problem in 3d Traceback (most recent call last): File "/mnt/exp.py", line 58, in \ LeftFace().mark(facets, 1) TypeError: mark(): incompa… --- ## [Error when Building dolfinx with Spack](https://fenicsproject.discourse.group/t/error-when-building-dolfinx-with-spack/17380)
**Author:** [@Hmd](https://fenicsproject.discourse.group/u/Hmd)\ **Replies:** 1\ **Last updated:** [April 16, 2025, 7:39am UTC](https://fenicsproject.discourse.group/t/error-when-building-dolfinx-with-spack/17380 "2025-04-16T07:39:34Z")
Hello, I encounter an error when installing Doflinx using Spack on a cluster with RockyLinux. It builds all other packages and fails when installing Dolfinx. I used the commands in the Readme. I’m using GCC 11.4.0. 3 … --- ## [Error in Solving Steady Navier Stokes Equation](https://fenicsproject.discourse.group/t/error-in-solving-steady-navier-stokes-equation/10224)
**Author:** [@Skywalker311](https://fenicsproject.discourse.group/u/Skywalker311)\ **Replies:** 7\ **Last updated:** [April 14, 2025, 4:55pm UTC](https://fenicsproject.discourse.group/t/error-in-solving-steady-navier-stokes-equation/10224 "2025-04-14T16:55:47Z")
I’m trying to convert my legacy FEniCS codes to FEniCSx to solve steady incompressible NSE with the Newton method for a Lid-Driven Cavity. I’m not able to set up the nonlinear solver properly. The FEniCS code is: # Def… --- ## [Confused about how to solve nonlinear stokes equation](https://fenicsproject.discourse.group/t/confused-about-how-to-solve-nonlinear-stokes-equation/17443)
**Author:** [@moooi](https://fenicsproject.discourse.group/u/moooi)\ **Replies:** 2\ **Last updated:** [April 12, 2025, 9:58am UTC](https://fenicsproject.discourse.group/t/confused-about-how-to-solve-nonlinear-stokes-equation/17443 "2025-04-12T09:58:25Z")
Hello everyone! I have struggled with nonlinear stokes problem for 2 weeks. :innocent: I use mixed\_element to define the FEspace, and I use NonlinearProblem solver to solve this problem. Really need your help!! … --- ## [Arity Errors when Running Code](https://fenicsproject.discourse.group/t/arity-errors-when-running-code/17431)
**Author:** [@Valencia\_Roberts](https://fenicsproject.discourse.group/u/Valencia_Roberts)\ **Replies:** 3\ **Last updated:** [April 11, 2025, 6:11pm UTC](https://fenicsproject.discourse.group/t/arity-errors-when-running-code/17431 "2025-04-11T18:11:59Z")
Hello everyone, I am working on a fluid-structure interface problem and I have managed to define my weak form as follows. I have the following problem: # Solid weak form (on subdomain 1) a\_solid = ufl.inner(sigma\_s(u\_s… --- ## [ValueError: vector::reserve when computing the points on the boundary of a domain](https://fenicsproject.discourse.group/t/valueerror-vector-reserve-when-computing-the-points-on-the-boundary-of-a-domain/17319)
**Author:** [@danielacos](https://fenicsproject.discourse.group/u/danielacos)\ **Replies:** 6\ **Last updated:** [April 10, 2025, 7:16pm UTC](https://fenicsproject.discourse.group/t/valueerror-vector-reserve-when-computing-the-points-on-the-boundary-of-a-domain/17319 "2025-04-10T19:16:39Z")
Dear all, I am trying to compute the values of a function on the top boundary of my domain by means of the following function, where I have used some snippets of code provided in the discourse group for previous questio… --- ## [Debugging Convergence Issues](https://fenicsproject.discourse.group/t/debugging-convergence-issues/17389)
**Author:** [@Valencia\_Roberts](https://fenicsproject.discourse.group/u/Valencia_Roberts)\ **Replies:** 1\ **Last updated:** [April 7, 2025, 6:33am UTC](https://fenicsproject.discourse.group/t/debugging-convergence-issues/17389 "2025-04-07T06:33:38Z")
Hello! I am working on a coupled fluid dynamics / elastic deformation system of PDEs, and I am running into convergence issues. I have tried updating the initial guess, playing around with parameters, non-dimensionalizi… --- ## [Inhomogeneous Stiffness Tensor UFL error](https://fenicsproject.discourse.group/t/inhomogeneous-stiffness-tensor-ufl-error/17290)
**Author:** [@Julian\_N](https://fenicsproject.discourse.group/u/Julian_N)\ **Replies:** 6\ **Last updated:** [March 31, 2025, 2:03pm UTC](https://fenicsproject.discourse.group/t/inhomogeneous-stiffness-tensor-ufl-error/17290 "2025-03-31T14:03:55Z")
Hello everyone, I try to solve the problem of linear elasticity on a simple domain with spatially varying stiffness tensor C(x) (non-isotropic). So far, I insert a scalar valued function f\_C(x) into the first three main… --- ## [The error in using the DG method to solve an elliptic problem](https://fenicsproject.discourse.group/t/the-error-in-using-the-dg-method-to-solve-an-elliptic-problem/17134)
**Author:** [@Chen-03](https://fenicsproject.discourse.group/u/Chen-03)\ **Replies:** 6\ **Last updated:** [March 4, 2025, 8:39am UTC](https://fenicsproject.discourse.group/t/the-error-in-using-the-dg-method-to-solve-an-elliptic-problem/17134 "2025-03-04T08:39:37Z")
Hi, everyone. I am using the DG method to solve a quasilinear elliptic equation, but I have encountered difficulties in implementation. The following is my code, and the error in the execution results is likely caused b… --- ## [Arity Mismatch error in mixed space with FENICS](https://fenicsproject.discourse.group/t/arity-mismatch-error-in-mixed-space-with-fenics/17042)
**Author:** [@M\_Jalili](https://fenicsproject.discourse.group/u/M_Jalili)\ **Replies:** 3\ **Last updated:** [February 21, 2025, 9:04pm UTC](https://fenicsproject.discourse.group/t/arity-mismatch-error-in-mixed-space-with-fenics/17042 "2025-02-21T21:04:18Z")
Dear. Researchers I am trying to solve coupled time dependent differential equations in Fenics. After running the program I have received the following error. I would be really appreciated if someone assist me to resol… [Next page](https://fenicsproject.discourse.group/c/errors/13.md?page=1)