diff --git a/lib/manager/npm/post-update/index.ts b/lib/manager/npm/post-update/index.ts
index 6549253827928a7a42448bd20042d3c8c49f5092..c69fc644afd38d01a80829980c199a9b00cb91b2 100644
--- a/lib/manager/npm/post-update/index.ts
+++ b/lib/manager/npm/post-update/index.ts
@@ -662,7 +662,7 @@ export async function getAdditionalFiles(
       }
       artifactErrors.push({
         lockFile: pnpmShrinkwrap,
-        stderr: res.stderr,
+        stderr: res.stderr || res.stdout,
       });
     } else {
       const existingContent = await getFile(