diff --git a/bqskit/compiler/compiler.py b/bqskit/compiler/compiler.py
index e68d5a6d4..df3b44002 100644
--- a/bqskit/compiler/compiler.py
+++ b/bqskit/compiler/compiler.py
@@ -393,6 +393,7 @@ def compile(
             request_data,
             logging_level,
             max_logging_depth,
+            data,
         )
         result = self.result(task_id)
 
diff --git a/bqskit/ir/opt/instantiaters/minimization.py b/bqskit/ir/opt/instantiaters/minimization.py
index be05ef52e..d4530c13a 100644
--- a/bqskit/ir/opt/instantiaters/minimization.py
+++ b/bqskit/ir/opt/instantiaters/minimization.py
@@ -8,8 +8,10 @@
 import numpy.typing as npt
 
 from bqskit.ir.gates.parameterized.unitary import VariableUnitaryGate
+from bqskit.ir.opt.cost.functions import HilbertSchmidtCostGenerator
 from bqskit.ir.opt.cost.functions import HilbertSchmidtResidualsGenerator
 from bqskit.ir.opt.cost.generator import CostFunctionGenerator
+from bqskit.ir.opt.cost.residual import ResidualsFunction
 from bqskit.ir.opt.instantiater import Instantiater
 from bqskit.ir.opt.minimizer import Minimizer
 from bqskit.ir.opt.minimizers.ceres import CeresMinimizer
@@ -107,6 +109,8 @@ def multi_start_instantiate_inplace(
         start_gen = RandomStartGenerator()
         starts = start_gen.gen_starting_points(num_starts, circuit, target)
         cost_fn = self.cost_fn_gen.gen_cost(circuit, target)
+        if isinstance(cost_fn, ResidualsFunction):
+            cost_fn = HilbertSchmidtCostGenerator().gen_cost(circuit, target)
         params_list = [self.instantiate(circuit, target, x0) for x0 in starts]
         params = sorted(params_list, key=lambda x: cost_fn(x))[0]
         circuit.set_params(params)
@@ -127,6 +131,8 @@ async def multi_start_instantiate_async(
         start_gen = RandomStartGenerator()
         starts = start_gen.gen_starting_points(num_starts, circuit, target)
         cost_fn = self.cost_fn_gen.gen_cost(circuit, target)
+        if isinstance(cost_fn, ResidualsFunction):
+            cost_fn = HilbertSchmidtCostGenerator().gen_cost(circuit, target)
         params_list = await get_runtime().map(
             self.instantiate,
             [circuit] * num_starts,
diff --git a/bqskit/runtime/worker.py b/bqskit/runtime/worker.py
index 7eb925b0c..15e22133c 100644
--- a/bqskit/runtime/worker.py
+++ b/bqskit/runtime/worker.py
@@ -371,15 +371,12 @@ def _handle_cancel(self, addr: RuntimeAddress) -> None:
         self._cancelled_task_ids.add(addr)
 
         # Remove all tasks that are children of `addr` from initialized tasks
-        for key, task in self._tasks.items():
+        for key, task in list(self._tasks.items()):
             if task.is_descendant_of(addr):
                 task.cancel()
-                for mailbox_id in self._tasks[key].owned_mailboxes:
+                for mailbox_id in task.owned_mailboxes:
                     self._mailboxes.pop(mailbox_id)
-        self._tasks = {
-            a: t for a, t in self._tasks.items()
-            if not t.is_descendant_of(addr)
-        }
+                self._tasks.pop(key, None)
 
         # Remove all tasks that are children of `addr` from delayed tasks
         self._delayed_tasks = [
@@ -466,7 +463,12 @@ def _try_step_next_ready_task(self) -> None:
         except StopIteration as e:
             self._process_task_completion(task, e.value)
 
-        except Exception:
+        except Exception as e:
+            if type(e) is RuntimeError:
+                for addr in self._cancelled_task_ids:
+                    if task.is_descendant_of(addr):
+                        return
+
             assert self._active_task is not None  # for type checker
 
             # Bubble up errors