Hello, I am doing RMA operation, but my MPI_Win_free got the following messages: Fatal error in MPI_Win_free: Invalid MPI_Win, error stack: MPI_Win_free(134): MPI_Win_free(win=0x7fffb1893028) failed MPI_Win_free(66).: Invalid MPI_Win =================================================================================== = BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES = EXIT CODE: 1 = CLEANING UP REMAINING PROCESSES = YOU CAN IGNORE THE BELOW CLEANUP MESSAGES =================================================================================== my rma operations shows below: MPI_Win_create(image_buff, 2*image_info->image_size * sizeof(uint16), sizeof(uint16), MPI_INFO_NULL, *MPI_FOR_WORLD, win); // MPI_FOR_WORLD is custom defined comm I just free it as: MPI_Win_free(&win); Do any one knows why? another weird thing is at the end of the program, I wrote: MPI_Comm_free(&MPI_FOR_WORLD); it also gave error: Fatal error in PMPI_Comm_free: Invalid communicator, error stack: PMPI_Comm_free(141): MPI_Comm_free(comm=0x7fff44a1535c) failed PMPI_Comm_free(91).: Null communicator Any suggestions are appreciate Thank you very much! -- Best Regards, Sufeng Niu ECASP lab, ECE department, Illinois Institute of Technology Tel: 312-731-7219