diff --git a/UPSTREAM_SYNC.md b/UPSTREAM_SYNC.md
index 7952634..1cc80d1 100644
--- a/UPSTREAM_SYNC.md
+++ b/UPSTREAM_SYNC.md
@@ -6,8 +6,8 @@ gitignored, so this file is the only durable record of what we last reviewed.
 
 - **Upstream**: https://github.com/ProtonDriveApps/sdk
 - **Reconciled subtree**: `client/cs/sdk/src`
-- **Pinned**: `36430318919c30fac42ec8577036a6d6e9de916f`
-- **Date**: 2026-06-26
+- **Pinned**: `f2496161c2f704b72511aa1b804961285993850c`
+- **Date**: 2026-07-10
 
 ## Workflow
 
@@ -23,3 +23,4 @@ gitignored, so this file is the only durable record of what we last reviewed.
 |------|-----------|--------|-------|
 | 2026-06-25 | initial pin `fb4173ab` | — | baseline; delta reviewed, 0 behavioral changes outstanding |
 | 2026-06-26 | `fb4173ab` → `36430318` | `36430318` | ported: enumeration returns `NodeUid`s (`enumerate_folder_children_node_uids` / `enumerate_trash_node_uids`), caller materializes via `enumerate_nodes`. noise dropped: BOM/deps/kt-enum-order/cs-account-refactor |
+| 2026-07-10 | `36430318` → `f2496161` | `9a1c39b3` | ported: validation check in `Thumbnail::new` returning `Result` instead of panicking. noise dropped: projects reorg / C# Account client move to incubating. deferred: device support (`32a8eed0`). |
diff --git a/crates/proton-drive-rs/src/node.rs b/crates/proton-drive-rs/src/node.rs
index 4384ab9..afba0d6 100644
--- a/crates/proton-drive-rs/src/node.rs
+++ b/crates/proton-drive-rs/src/node.rs
@@ -138,11 +138,21 @@ pub struct Thumbnail {
 
 impl Thumbnail {
     /// Create a thumbnail from rendered image bytes.
-    pub fn new(thumbnail_type: ThumbnailType, content: Vec<u8>) -> Self {
-        Self {
+    ///
+    /// Returns an error if the `content` is empty.
+    pub fn new(
+        thumbnail_type: ThumbnailType,
+        content: Vec<u8>,
+    ) -> Result<Self, proton_sdk::error::ProtonError> {
+        if content.is_empty() {
+            return Err(proton_sdk::error::ProtonError::invalid_operation(
+                "Thumbnail content must not be empty.",
+            ));
+        }
+        Ok(Self {
             thumbnail_type,
             content,
-        }
+        })
     }
 }
 
diff --git a/crates/proton-drive-rs/tests/live_transfer_ops.rs b/crates/proton-drive-rs/tests/live_transfer_ops.rs
index c795a2d..aaa2ff4 100644
--- a/crates/proton-drive-rs/tests/live_transfer_ops.rs
+++ b/crates/proton-drive-rs/tests/live_transfer_ops.rs
@@ -260,8 +260,8 @@ async fn thumbnails_upload_and_fetch() {
     let thumb_small: Vec<u8> = (0..4096).map(|i| (i * 13 + 1) as u8).collect();
     let thumb_preview: Vec<u8> = (0..8192).map(|i| (i * 17 + 3) as u8).collect();
     let thumbnails = vec![
-        Thumbnail::new(ThumbnailType::Thumbnail, thumb_small.clone()),
-        Thumbnail::new(ThumbnailType::Preview, thumb_preview.clone()),
+        Thumbnail::new(ThumbnailType::Thumbnail, thumb_small.clone()).unwrap(),
+        Thumbnail::new(ThumbnailType::Preview, thumb_preview.clone()).unwrap(),
     ];
 
     let payload = b"file body for thumbnail upload".to_vec();