diff --git a/executorlib/interactive/executor.py b/executorlib/interactive/executor.py
index ed32d31f..503ab9fd 100644
--- a/executorlib/interactive/executor.py
+++ b/executorlib/interactive/executor.py
@@ -29,7 +29,7 @@
 from executorlib.standalone.thread import RaisingThread
 
 try:  # The PyFluxExecutor requires flux-base to be installed.
-    from executorlib.interactive.flux import FluxPythonSpawner
+    from executorlib.interactive.flux import FluxPythonSpawner, validate_max_workers
 except ImportError:
     pass
 
@@ -226,13 +226,19 @@ def create_executor(
         resource_dict["flux_executor_nesting"] = flux_executor_nesting
         if block_allocation:
             resource_dict["init_function"] = init_function
+            max_workers = validate_number_of_cores(
+                max_cores=max_cores,
+                max_workers=max_workers,
+                cores_per_worker=cores_per_worker,
+                set_local_cores=False,
+            )
+            validate_max_workers(
+                max_workers=max_workers,
+                cores=cores_per_worker,
+                threads_per_core=resource_dict["threads_per_core"],
+            )
             return InteractiveExecutor(
-                max_workers=validate_number_of_cores(
-                    max_cores=max_cores,
-                    max_workers=max_workers,
-                    cores_per_worker=cores_per_worker,
-                    set_local_cores=False,
-                ),
+                max_workers=max_workers,
                 executor_kwargs=resource_dict,
                 spawner=FluxPythonSpawner,
             )
diff --git a/executorlib/interactive/flux.py b/executorlib/interactive/flux.py
index 472a4792..fd674087 100644
--- a/executorlib/interactive/flux.py
+++ b/executorlib/interactive/flux.py
@@ -1,11 +1,25 @@
 import os
 from typing import Optional
 
+import flux
 import flux.job
 
 from executorlib.standalone.interactive.spawner import BaseSpawner
 
 
+def validate_max_workers(max_workers, cores, threads_per_core):
+    handle = flux.Flux()
+    cores_total = flux.resource.list.resource_list(handle).get().up.ncores
+    cores_requested = max_workers * cores * threads_per_core
+    if cores_total < cores_requested:
+        raise ValueError(
+            "The number of requested cores is larger than the available cores "
+            + str(cores_total)
+            + " < "
+            + str(cores_requested)
+        )
+
+
 class FluxPythonSpawner(BaseSpawner):
     """
     A class representing the FluxPythonInterface.
diff --git a/tests/test_executor_backend_flux.py b/tests/test_executor_backend_flux.py
index 8ab11569..b9d45ee7 100644
--- a/tests/test_executor_backend_flux.py
+++ b/tests/test_executor_backend_flux.py
@@ -113,3 +113,13 @@ def test_internal_memory(self):
             self.assertFalse(f.done())
             self.assertEqual(f.result(), np.array([5]))
             self.assertTrue(f.done())
+
+    def test_validate_max_workers(self):
+        with self.assertRaises(ValueError):
+            Executor(
+                max_workers=10,
+                resource_dict={"cores": 10, "threads_per_core": 10},
+                flux_executor=self.executor,
+                backend="flux_allocation",
+                block_allocation=True,
+            )