diff --git a/lib/spack/spack/installer.py b/lib/spack/spack/installer.py
index 3ddb08de8a1..1823c34b8a6 100644
--- a/lib/spack/spack/installer.py
+++ b/lib/spack/spack/installer.py
@@ -2226,8 +2226,11 @@ def complete_task(task) -> None:
             keep_prefix = install_args.get("keep_prefix")
             action = self._install_action(task)
             try:
-                self._complete_task(task, install_status)
-                active_tasks.remove(task)
+                try:
+                    self._complete_task(task, install_status)
+                finally:
+                    # Remove task from active_tasks on error or success
+                    active_tasks.remove(task)
 
                 # If we installed then we should keep the prefix
                 stop_before_phase = getattr(pkg, "stop_before_phase", None)
diff --git a/lib/spack/spack/test/installer.py b/lib/spack/spack/test/installer.py
index f9f3d20f273..d3fe3bb3bd3 100644
--- a/lib/spack/spack/test/installer.py
+++ b/lib/spack/spack/test/installer.py
@@ -984,6 +984,7 @@ class MyBuildException(Exception):
 
 _old_complete_task = None
 
+
 def _install_fail_my_build_exception(installer, task, install_status, **kwargs):
     if task.pkg.name == "pkg-a":
         print("Raising MyBuildException for pkg-a")
@@ -995,13 +996,13 @@ def _install_fail_my_build_exception(installer, task, install_status, **kwargs):
 def test_install_fail_single(install_mockery, mock_fetch, monkeypatch):
     """Test expected results for failure of single package."""
     global _old_complete_task
-    
+
     installer = create_installer(["pkg-a"], {"fake": True})
 
     # Raise a KeyboardInterrupt error to trigger early termination
     _old_complete_task = inst.PackageInstaller._complete_task
     monkeypatch.setattr(inst.PackageInstaller, "_complete_task", _install_fail_my_build_exception)
-    
+
     with pytest.raises(MyBuildException, match="mock internal package build error for pkg-a"):
         installer.install()