# Error in loading xdmf file: unable to recognise cell type

**URL:** <https://fenicsproject.discourse.group/t/error-in-loading-xdmf-file-unable-to-recognise-cell-type/8683>\
**Category:** I/O\
**Created:** [July 3, 2022, 3:13pm UTC](https://fenicsproject.discourse.group/t/error-in-loading-xdmf-file-unable-to-recognise-cell-type/8683 "2022-07-03T15:13:08Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![unica111](https://avatars.discourse-cdn.com/v4/letter/u/977dab/32.png) [@unica111](https://fenicsproject.discourse.group/u/unica111)\
**Post date:** [July 3, 2022, 3:13pm UTC](https://fenicsproject.discourse.group/t/error-in-loading-xdmf-file-unable-to-recognise-cell-type/8683/1 "2022-07-03T15:13:08Z")

</div>

Hello,

I am trying to load a mesh from an xdmf file generating from the following code.

```auto
import pygmsh

with pygmsh.occ.Geometry() as geom:
    geom.characteristic_length_min = 0.1
    geom.characteristic_length_max = 0.1
    rectangle1 = geom.add_rectangle([0.0, 0.0, 0.0], 1.0, 0.5)
    rectangle2 = geom.add_rectangle([0.0, 0.5, 0.0], 1.0, 0.5)
    geom.boolean_fragments(rectangle1, rectangle2)
    mesh = geom.generate_mesh()

mesh.write("out.xdmf")

```

Then I use “infile” to read the mesh into fenics by below code.

```auto
from fenics import *

mesh = Mesh()

with XDMFFile("out.xdmf") as infile:
    infile.read(mesh)

```

But I encounter an error below:

Error: Unable to recognise cell type.  
Reason: Unknown value “mixed”.  
Where: This error was encountered inside XDMFFILE.cpp.  
Process: 0

May I enquire that how can I resolve this error? Thank you.

---

<div class="post-metadata">

**Author:** ![dokken](https://yyz2.discourse-cdn.com/free1/user_avatar/fenicsproject.discourse.group/dokken/32/1560_2.png) [@dokken](https://fenicsproject.discourse.group/u/dokken)\
**Post date:** [July 3, 2022, 3:34pm UTC](https://fenicsproject.discourse.group/t/error-in-loading-xdmf-file-unable-to-recognise-cell-type/8683/2 "2022-07-03T15:34:55Z")

</div>

This has been covered in several other topics: [Transitioning from mesh.xml to mesh.xdmf, from dolfin-convert to meshio](https://fenicsproject.discourse.group/t/transitioning-from-mesh-xml-to-mesh-xdmf-from-dolfin-convert-to-meshio/412)  
[Line mesh in a 2D space - #2 by dokken](https://fenicsproject.discourse.group/t/line-mesh-in-a-2d-space/2066/2)  
Etc.