Hi everyone, I am having trouble with using SNES from petsc4py in PETSc 3.22. The problem is similar to https://gitlab.com/petsc/petsc/-/issues/1611 and related to the readonly access of x. Particularly, in my application, based on FEniCS, I want to solve a nonlinear PDE. Therefore, in my callbacks, I want to set the vector of DoFs of my FEniCS function to x with a line like self.u.vector().vec().setArray(x) However, this now raises the error [0] Vector 'Vec_0x84000003_0' (argument #1) was locked for read-only access in unknown_function() at unknown file:0 (line numbers only accurate to function begin) I believe that this is a consequence of https://gitlab.com/petsc/petsc/-/merge_requests/7567#22c226fc29b6fc9dc5781b0 aff4dcc70ac6c3489, but I did not find any information on how to remove the lock from the vector or how I can set use x to update the vector of my function. Using xx = x.getArray(readonly=True) as described in https://gitlab.com/petsc/petsc/-/issues/1611 does not work either, as calling self.u.vector().vec().setArray(xx) then fails with the same error message. Does anyone have an idea how to fix this? Thanks a lot in advance, Sebastian -- Dr. Sebastian Blauth Fraunhofer-Institut für Techno- und Wirtschaftsmathematik ITWM Abteilung Transportvorgänge Fraunhofer-Platz 1, 67663 Kaiserslautern Telefon: +49 631 31600-4968 <mailto:[email protected]> [email protected] <https://www.itwm.fraunhofer.de> https://www.itwm.fraunhofer.de