The qp_alloc_hypercall() routine errors out while having VMCI and Fault Tolerance features enabled

Solution Verified - Updated -


The following messages are repeated in the kernel ring buffer of the ESXi guest VM:

kernel: Could not attach to queue pair with -20
kernel: qp_alloc_hypercall result = -20


  • Red Hat Enterprise Linux 7 and 8
  • VMWare ESXi hypervisor
  • Fault Tolerance and VMCI features enabled for VM

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