diff --git a/python-client/wmill/wmill/s3_reader.py b/python-client/wmill/wmill/s3_reader.py
index 62161a6946..557bc9d200 100644
--- a/python-client/wmill/wmill/s3_reader.py
+++ b/python-client/wmill/wmill/s3_reader.py
@@ -22,6 +22,17 @@ class S3BufferedReader(BufferedReader):
 
     def __enter__(self):
         reader = self._context_manager.__enter__()
+        if reader.status_code >= 400:
+            error_bytes = reader.read()
+            try:
+                error_text = error_bytes.decode('utf-8')
+            except UnicodeDecodeError:
+                error_text = str(error_bytes)
+            raise httpx.HTTPStatusError(
+                f"Failed to load S3 file: {reader.status_code} {reader.reason_phrase} - {error_text}",
+                request=reader.request,
+                response=reader
+            )
         self._iterator = reader.iter_bytes()
         return self
 
diff --git a/typescript-client/client.ts b/typescript-client/client.ts
index 25de187598..f2388d2962 100644
--- a/typescript-client/client.ts
+++ b/typescript-client/client.ts
@@ -717,7 +717,7 @@ export async function loadS3FileStream(
   const queryParams = new URLSearchParams(params);
 
   // We use raw fetch here b/c OpenAPI generated client doesn't handle Blobs nicely
-  const fileContentBlob = await fetch(
+  const response = await fetch(
     `${
       OpenAPI.BASE
     }/w/${getWorkspace()}/job_helpers/download_s3_file?${queryParams}`,
@@ -728,7 +728,16 @@ export async function loadS3FileStream(
       },
     }
   );
-  return fileContentBlob.blob();
+
+  // Check if the response was successful
+  if (!response.ok) {
+    const errorText = await response.text();
+    throw new Error(
+      `Failed to load S3 file: ${response.status} ${response.statusText} - ${errorText}`
+    );
+  }
+
+  return response.blob();
 }
 
 /**