From c763da4cfba9dd15b30a099dc1a5ddc71fd246d5 Mon Sep 17 00:00:00 2001
From: Ben Grande <ben.grande.b@gmail.com>
Date: Wed, 3 Sep 2025 15:32:21 +0200
Subject: [PATCH] Inform how to debug failed preload startup

The "domain-start-failed" has to be fired before the domain is killed,
as the qube is unregistered from clients when it is removed/powered off.

Fixes: https://github.com/QubesOS/qubes-issues/issues/10200
For: https://github.com/QubesOS/qubes-issues/issues/1512
---
 qubes/vm/dispvm.py  | 6 ++++--
 qubes/vm/qubesvm.py | 9 ++++-----
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/qubes/vm/dispvm.py b/qubes/vm/dispvm.py
index f985959f9..6ecb0493a 100644
--- a/qubes/vm/dispvm.py
+++ b/qubes/vm/dispvm.py
@@ -373,11 +373,13 @@ async def on_domain_started_dispvm(
         except asyncio.TimeoutError:
             raise qubes.exc.QubesException(
                 "Timed out call to '%s' after '%d' seconds during preload "
-                "startup" % (service, timeout)
+                "startup" % (rpc, timeout)
             )
         except (subprocess.CalledProcessError, qubes.exc.QubesException):
             raise qubes.exc.QubesException(
-                "Error on call to '%s' during preload startup" % service
+                "Error on call to '%s' during preload startup. To debug, run "
+                "the following on a new disposable of '%s': systemctl "
+                "--failed" % (rpc, self.template)
             )
 
         if not self.preload_requested:
diff --git a/qubes/vm/qubesvm.py b/qubes/vm/qubesvm.py
index 4dd6c1dad..d26fded48 100644
--- a/qubes/vm/qubesvm.py
+++ b/qubes/vm/qubesvm.py
@@ -1548,6 +1548,10 @@ async def start(
 
             except Exception as exc:  # pylint: disable=bare-except
                 self.log.error("Start failed: %s", str(exc))
+                # let anyone receiving domain-pre-start know that startup failed
+                await self.fire_event_async(
+                    "domain-start-failed", reason=str(exc)
+                )
                 # This avoids losing the exception if an exception is
                 # raised in self.kill(), because the vm is not
                 # running or paused
@@ -1555,11 +1559,6 @@ async def start(
                     await self.kill()
                 except qubes.exc.QubesVMNotStartedError:
                     pass
-
-                # let anyone receiving domain-pre-start know that startup failed
-                await self.fire_event_async(
-                    "domain-start-failed", reason=str(exc)
-                )
                 raise
 
         return self