diff --git a/pkg/downloader/manager.go b/pkg/downloader/manager.go
index 2b7d3e40a..08f0d3232 100644
--- a/pkg/downloader/manager.go
+++ b/pkg/downloader/manager.go
@@ -736,31 +736,50 @@ func (m *Manager) findChartURL(name, version, repoURL, repoName string, repos ma
 
 	// First, try to look up the repository by name. This ensures correct
 	// credentials are used when multiple repositories share the same URL.
+	// When a repo name is provided and exists in the repos map, the lookup
+	// is authoritative: if the chart is not found or URL resolution fails,
+	// an error is returned rather than silently falling back to URL-based
+	// scanning. If the named repo is not in the repos map (e.g. repos from
+	// ensureMissingRepos are not persisted to repositories.yaml), we fall
+	// through to URL-based scanning for backward compatibility.
 	if repoName != "" {
 		if cr, ok := repos[repoName]; ok {
 			var entry repo.ChartVersions
 			entry, err = findEntryByName(name, cr)
-			if err == nil {
-				var ve *repo.ChartVersion
-				ve, err = findVersionedEntry(version, entry)
-				if err == nil {
-					url, err = repo.ResolveReferenceURL(cr.Config.URL, ve.URLs[0])
-					if err == nil {
-						username = cr.Config.Username
-						password = cr.Config.Password
-						passCredentialsAll = cr.Config.PassCredentialsAll
-						insecureSkipTLSVerify = cr.Config.InsecureSkipTLSVerify
-						caFile = cr.Config.CAFile
-						certFile = cr.Config.CertFile
-						keyFile = cr.Config.KeyFile
-						return
-					}
-				}
+			if err != nil {
+				err = fmt.Errorf("chart %q not found in repository %q", name, repoName)
+				return
+			}
+
+			var ve *repo.ChartVersion
+			ve, err = findVersionedEntry(version, entry)
+			if err != nil {
+				err = fmt.Errorf("chart %q version %q not found in repository %q", name, version, repoName)
+				return
 			}
+
+			url, err = repo.ResolveReferenceURL(cr.Config.URL, ve.URLs[0])
+			if err != nil {
+				return
+			}
+
+			username = cr.Config.Username
+			password = cr.Config.Password
+			passCredentialsAll = cr.Config.PassCredentialsAll
+			insecureSkipTLSVerify = cr.Config.InsecureSkipTLSVerify
+			caFile = cr.Config.CAFile
+			certFile = cr.Config.CertFile
+			keyFile = cr.Config.KeyFile
+			return
 		}
+		// Repo name provided but not in the repos map.
+		// Fall through to URL-based scanning for backward compatibility
+		// (handles repos generated by ensureMissingRepos).
 	}
 
-	// Fall back to scanning repos by URL for backward compatibility.
+	// Fall back to scanning repos by URL for backward compatibility
+	// (only when no repo name was specified, or the named repo is not in
+	// the repos map).
 	for _, cr := range repos {
 		if urlutil.Equal(repoURL, cr.Config.URL) {
 			var entry repo.ChartVersions
diff --git a/pkg/downloader/manager_test.go b/pkg/downloader/manager_test.go
index 0b1c4db9a..cd51b645a 100644
--- a/pkg/downloader/manager_test.go
+++ b/pkg/downloader/manager_test.go
@@ -202,9 +202,6 @@ repositories:
 		t.Fatal(err)
 	}
 
-	// Find with repo-alias-1 and a repoURL that differs from cr.Config.URL
-	// (no trailing slash vs with trailing slash). Should still resolve correctly
-	// because it uses cr.Config.URL as the base for relative chart URLs.
 	repoURL := "http://example.com/charts"
 	name := "alpine"
 	version := "0.1.0"
@@ -261,6 +258,29 @@ repositories:
 	if username == "" {
 		t.Error("Expected non-empty username from URL-based fallback")
 	}
+
+	// --- Authoritative name-based lookup: error cases ---
+
+	// Repo name provided but not in repos map: falls through to URL scan
+	// (backward compatibility for repos generated by ensureMissingRepos).
+	_, _, _, _, _, _, _, _, err = m.findChartURL(name, version, repoURL, "nonexistent", repos)
+	if err != nil {
+		t.Errorf("Expected fallback to URL scan for repo not in map, got error: %v", err)
+	}
+
+	// Repo name valid but chart not found in that specific repo: must error,
+	// must not fall through to URL-based scanning.
+	_, _, _, _, _, _, _, _, err = m.findChartURL("nonexistent-chart", version, repoURL, "repo-alias-1", repos)
+	if err == nil {
+		t.Error("Expected error for nonexistent chart in named repo, got nil")
+	}
+
+	// Repo name valid, chart exists, but version not found: must error,
+	// must not fall through to URL-based scanning.
+	_, _, _, _, _, _, _, _, err = m.findChartURL(name, "99.99.99", repoURL, "repo-alias-1", repos)
+	if err == nil {
+		t.Error("Expected error for nonexistent version in named repo, got nil")
+	}
 }
 
 func TestGetRepoNames(t *testing.T) {