diff --git a/scripts/generate_pack.py b/scripts/generate_pack.py
index 5c00c398..c0c8659a 100644
--- a/scripts/generate_pack.py
+++ b/scripts/generate_pack.py
@@ -2088,6 +2088,7 @@ def _run_manifest_mode(
     else:
         variants = [(args.source, args.required_only)]
 
+    failed: list[str] = []
     for source, required_only in variants:
         for group_platforms, representative in groups:
             print(f"\nGenerating manifest for {representative} [source={source}]...")
@@ -2155,6 +2156,13 @@ def _run_manifest_mode(
                         print(f"  {alias_path}: alias of {representative}")
             except (FileNotFoundError, OSError, yaml.YAMLError) as e:
                 print(f"  ERROR: {e}")
+                failed.append(representative)
+
+    # A platform whose manifest could not be built has none, and install.py
+    # serves whatever an older run left there: that is a failed run.
+    if failed:
+        print(f"ERROR: no manifest for {', '.join(sorted(set(failed)))}")
+        sys.exit(1)
 
 
 @contextlib.contextmanager
@@ -2265,6 +2273,7 @@ def _run_platform_packs(
     else:
         variants = [(args.source, args.required_only)]
 
+    failed: list[str] = []
     for source, required_only in variants:
         for group_platforms, representative in groups:
             aliases = [p for p in group_platforms if p != representative]
@@ -2346,6 +2355,7 @@ def _run_platform_packs(
                         print(f"  Renamed -> {os.path.basename(new_path)}")
             except (FileNotFoundError, OSError, yaml.YAMLError) as e:
                 print(f"  ERROR: {e}")
+                failed.append(representative)
 
     print("\nVerifying packs and generating manifests...")
     skip_conf = bool(system_filter or args.split)
@@ -2369,6 +2379,11 @@ def _run_platform_packs(
                     regions=getattr(args, "regions", None),
                 )
                 all_ok = all_ok and ok
+    if failed:
+        # Verification only sees the ZIPs that exist; a pack that was never
+        # written does not fail it.
+        print(f"ERROR: no pack for {', '.join(sorted(set(failed)))}")
+        sys.exit(1)
     if not all_ok:
         print("WARNING: some packs have verification errors")
         sys.exit(1)
diff --git a/tests/test_pack_failures.py b/tests/test_pack_failures.py
new file mode 100644
index 00000000..9d6c897d
--- /dev/null
+++ b/tests/test_pack_failures.py
@@ -0,0 +1,65 @@
+"""A platform whose pack or manifest raised fails the run.
+
+Both loops printed ERROR and moved on. The exit code came from the packs
+present on disk, so a pack never written, or a manifest install.py would
+keep serving from an older run, left the run green.
+"""
+
+from __future__ import annotations
+
+import argparse
+import os
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+from unittest import mock
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+import generate_pack as gp  # noqa: E402
+
+
+def _boom(*args, **kwargs):
+    raise OSError(28, "No space left on device")
+
+
+class FailedPlatformFailsTheRun(unittest.TestCase):
+    def setUp(self):
+        previous = os.getcwd()
+        os.chdir(REPO_ROOT)
+        self.addCleanup(os.chdir, previous)
+        (REPO_ROOT / "tmp").mkdir(exist_ok=True)
+        self.tmp = tempfile.TemporaryDirectory(dir=REPO_ROOT / "tmp")
+        self.addCleanup(self.tmp.cleanup)
+
+    def _args(self) -> argparse.Namespace:
+        return argparse.Namespace(
+            all_variants=False, source="full", required_only=False,
+            platforms_dir="platforms", target=None, split=False,
+            include_extras=False, emulators_dir="emulators", regions=[],
+            one_per_slot=False, offline=True, bios_dir="bios",
+            output_dir=self.tmp.name, verify_packs=False,
+        )
+
+    def test_pack_mode(self):
+        with mock.patch.object(gp, "generate_pack", _boom), \
+                mock.patch.object(gp, "verify_and_finalize_packs", return_value=True):
+            with self.assertRaises(SystemExit) as ctx:
+                gp._run_platform_packs(
+                    self._args(), [(["retropie"], "retropie")], {}, {}, {}, {}, {}, None
+                )
+        self.assertEqual(ctx.exception.code, 1)
+
+    def test_manifest_mode(self):
+        with mock.patch.object(gp, "generate_manifest", _boom):
+            with self.assertRaises(SystemExit) as ctx:
+                gp._run_manifest_mode(
+                    self._args(), [(["retropie"], "retropie")], {}, {}, {}, {}
+                )
+        self.assertEqual(ctx.exception.code, 1)
+
+
+if __name__ == "__main__":
+    unittest.main()