Hi Kenneth, Running the same test with mpich@develop, I still see the following errors in a typical outfile : [sas4990@quser10 mdb6i63]$ cat lat_10 ---------------------------------------- ... ---------------------------------------- slurmstepd: error: mpi/pmi2: no value for key in req slurmstepd: error: mpi/pmi2: no value for key in req slurmstepd: error: mpi/pmi2: no value for key in req [1574880837.368994] [qnode5038:4743 :0] ucp_context.c:1131 UCX WARN UCP version is incompatible, required: 1.5, actual: 1.4 (release 0) slurmstepd: error: mpi/pmi2: no value for key in req slurmstepd: error: mpi/pmi2: no value for key in req [1574880837.377860] [qnode5039:4546 :0] ucp_context.c:1131 UCX WARN UCP version is incompatible, required: 1.5, actual: 1.4 (release 0) slurmstepd: error: mpi/pmi2: no value for key in req slurmstepd: error: mpi/pmi2: no value for key in req slurmstepd: error: mpi/pmi2: no value for key in req slurmstepd: error: mpi/pmi2: no value for key in req slurmstepd: error: mpi/pmi2: no value for key in req # OSU MPI_Get latency Test v5.6.1 # Window creation: MPI_Win_allocate # Synchronization: MPI_Win_flush # Size Latency (us) 1 2.13 .... Since UCX is a vendored dependency of MPICH, why is MPICH complaining about an incompatible UCX version ? Thank You, Sajid Ali | PhD Candidate Applied Physics Northwestern University s-sajid-ali.github.io