The currently included PETSc tarball is version 3.5.2 which uses the type name
MPI_Handler_function in a call to the (modern) function
MPI_Comm_create_errhandler instead of the modern
OpenMPI 4.X no longer provides this type by default and requires that it is built with
--enable-mpi1-compatibility. Thus PETSc may not build on clusters providing OpenMPI 4.X that do not include this flag. The included OpenMPI tarball is built with this option as of git hash 8e7f753 "MPI: enable MPI-1 compatibility" of ExternalLibraries-MPI.