diff --git a/xen/common/sched/core.c b/xen/common/sched/core.c
index ee24cc28f6..17e7f52169 100644
--- a/xen/common/sched/core.c
+++ b/xen/common/sched/core.c
@@ -745,6 +745,38 @@ int sched_move_domain(struct domain *d, struct cpupool *c)
 
     for ( unit_idx = 0; unit_idx < n_units; unit_idx++ )
     {
+        /*
+         * A vcpu slot can be missing if creation failed partway
+         * through. A dying domain is being torn down regardless, so
+         * skip the unit -- but a domain that isn't dying still needs
+         * every vcpu it has schedulable, so fail instead of silently
+         * dropping some of them.
+         */
+        bool vcpu_failed = false;
+
+        for ( unsigned int i = 0;
+              i < gran && unit_idx * gran + i < d->max_vcpus; i++ )
+        {
+            if ( !d->vcpu[unit_idx * gran + i] )
+            {
+                vcpu_failed = true;
+                break;
+            }
+        }
+
+        if ( vcpu_failed )
+        {
+            if ( !d->is_dying )
+            {
+                sched_move_domain_cleanup(c->sched, new_units, domdata);
+                rcu_read_unlock(&sched_res_rculock);
+
+                return -EINVAL;
+            }
+
+            continue;
+        }
+
         unit = sched_alloc_unit_mem();
         if ( unit )
         {