diff --git a/frontend/src/pages/Dms.tsx b/frontend/src/pages/Dms.tsx
index fb7440b..fa168af 100644
--- a/frontend/src/pages/Dms.tsx
+++ b/frontend/src/pages/Dms.tsx
@@ -104,7 +104,7 @@ export function DmsPage() {
       const folderList = await fetchFolders();
       setFolders(folderList);
     } catch (err) {
-      const msg = err instanceof Error ? err.message : String(err);
+      const msg = err instanceof Error ? err.message : (typeof err === 'string' ? err : JSON.stringify(err));
       setError(msg);
     }
     setLoadingFolders(false);
@@ -148,7 +148,7 @@ export function DmsPage() {
         setFiles(result);
       }
     } catch (err) {
-      const msg = err instanceof Error ? err.message : String(err);
+      const msg = err instanceof Error ? err.message : (typeof err === 'string' ? err : JSON.stringify(err));
       if (currentLoadId.current === loadId) {
         setError(msg);
         setFiles([]);
@@ -503,7 +503,7 @@ export function DmsPage() {
     <div className="flex flex-col h-full" data-testid="dms-page">
       {error && (
         <div className="mb-2 p-3 bg-danger-50 border border-danger-200 rounded-md" role="alert" data-testid="dms-error">
-          <p className="text-sm text-danger-700">{error}</p>
+          <p className="text-sm text-danger-700">{String(error)}</p>
         </div>
       )}