Hello,
I am solving an elasticity problem in which the domain is a rectangle (150x120) with two circular voids (radius = 4) (shaped like a videotape). I would like to apply Dirichlet BC on the boundary of the voids and to apply other Dirichlet BC on the right boundary of the rectangle. When I run my code I get the error:
*** Warning: Found no facets matching domain for boundary condition.
I checked the similar question asked here:https://fenicsproject.discourse.group/t/dirichlet-bcs-on-an-annulus/1711
but I was hoping for a new answer since 2 years have passed. I understand the problem is probably with the BC on the voids.
So, the way I wrote it is:

As you have not supplied your mesh file, it is not very easy to help you. Please not that if you create your mesh with an external mesh creator (say GMSH) you can mark your boundaries in the creation step and import them, as covered in:

and the error disappeared. Unfortunately, now I cannot assign any label to boundaries and get an error for “n”. I tried to fix it as dokken suggested by generating the mesh on freefem (.mesh file) and labeling there the various boundaries.

As you are not staying what error you are obtaining, and you do not provide a minimal code example reproducing the error, I cannot provide you much more help.