diff --git a/controller/internal/stacks/update.go b/controller/internal/stacks/update.go
index 49f2d96..98a46a6 100644
--- a/controller/internal/stacks/update.go
+++ b/controller/internal/stacks/update.go
@@ -1429,7 +1429,7 @@ func (m *Manager) RecoverUpdates() []string {
 			// v0.263.0: a power cut DURING the undo. Resumed like `starting` — the undo runs again from
 			// the copies (still there: they are removed only after the undo succeeded) and then probes.
 			// Never "done": what ran last was a failed new version.
-			m.logger.Printf("[WARN] [stacks] update recovery: %s was interrupted while UNDOING (started %s) — marking it Updating and RESUMING the undo", name, e.StartedAt.Format(time.RFC3339))
+			m.logger.Printf("[WARN] [stacks] update recovery: %s was interrupted while %s (started %s) — marking it Updating and RESUMING the undo", name, map[string]string{UpdatePhaseUndoing: "UNDOING", UpdatePhaseConverting: "CONVERTING its database (the volume may be emptied)"}[e.Phase], e.StartedAt.Format(time.RFC3339))
 			m.mu.Lock()
 			if s, ok := m.stacks[name]; ok {
 				s.Updating, s.UpdateError, s.updateHeld = true, "", false