diff --git a/crates/contracts/src/profession_shared.rs b/crates/contracts/src/profession_shared.rs
index 75d7b7e..2d3ceaf 100644
--- a/crates/contracts/src/profession_shared.rs
+++ b/crates/contracts/src/profession_shared.rs
@@ -887,7 +887,10 @@ async fn upload_document(
     {
         Ok(url) => url,
         Err(e) => {
-            tracing::error!("B2 upload failed: {}", e);
+            // {:?} on an anyhow::Error prints the full context chain, not just
+            // the outermost ".context()" message — that's what actually names
+            // the root cause (auth, DNS, timeout, etc.).
+            tracing::error!("B2 upload failed: {:?}", e);
             return (StatusCode::INTERNAL_SERVER_ERROR, Json(serde_json::json!({ "error": "File upload failed" }))).into_response();
         }
     };