diff --git a/chrome/content/zotero/xpcom/sync/syncEngine.js b/chrome/content/zotero/xpcom/sync/syncEngine.js
index ed55c2f492..97936deaf9 100644
--- a/chrome/content/zotero/xpcom/sync/syncEngine.js
+++ b/chrome/content/zotero/xpcom/sync/syncEngine.js
@@ -149,6 +149,7 @@ Zotero.Sync.Data.Engine.prototype.start = Zotero.Promise.coroutine(function* ()
 				throw e;
 			}
 			Zotero.debug("Upload failed -- performing download", 2);
+			Zotero.debug(e, 1);
 			downloadResult = yield this._startDownload();
 			Zotero.debug("Download result is " + downloadResult, 4);
 			throw e;