This comes from the new type checking for Fortran code. I suggest you just call MPI_Barrier() using MPI_COMM_WORLD from Fortran.
Barry > On Nov 6, 2018, at 11:37 PM, Marius Buerkle via petsc-users > <petsc-users@mcs.anl.gov> wrote: > > Hi > > When calling PetscBarrier from fortran using "call > PetscBarrier(PETSC_NULL_MAT,ierr)" with latest petsc version 3.10.2, I get > the following error "Error: Type mismatch in argument ‘a’ at (1); passed > TYPE(tmat) to INTEGER(8)". I compiled petsc not with integer(8). It work with > previous versions. > > best, > Marius