diff --git a/chrome/content/zotero/xpcom/schema.js b/chrome/content/zotero/xpcom/schema.js
index b4877e3421..baeab1a0b9 100644
--- a/chrome/content/zotero/xpcom/schema.js
+++ b/chrome/content/zotero/xpcom/schema.js
@@ -1514,6 +1514,18 @@ Zotero.Schema = new function(){
 				url += '&m=' + mode;
 			}
 			
+			// TEMP: DB diagnostics
+			let exists = yield Zotero.DB.tableExists('transactionSets');
+			url += "&ts=" + (exists ? "1" : "0");
+			if (exists) {
+				Zotero.logError("DB table 'transactionSets' still exists");
+			}
+			exists = yield Zotero.DB.tableExists('dbDebug1');
+			url += "&db1=" + (exists ? "1" : "0");
+			if (!exists) {
+				Zotero.logError("DB table 'dbDebug1' does not exist");
+			}
+			
 			// Send list of installed styles
 			var styles = Zotero.Styles.getAll();
 			var styleTimestamps = [];
@@ -3025,6 +3037,10 @@ Zotero.Schema = new function(){
 				yield Zotero.DB.queryAsync(`DELETE FROM itemRelations WHERE predicateID=(SELECT predicateID FROM relationPredicates WHERE predicate='owl:sameAs') AND object LIKE ?`, 'http://zotero.org/users/local/%');
 			}
 			
+			else if (i == 109) {
+				yield Zotero.DB.queryAsync("CREATE TABLE dbDebug1 (\n    a INTEGER PRIMARY KEY\n)");
+			}
+			
 			// If breaking compatibility or doing anything dangerous, clear minorUpdateFrom
 		}
 		
diff --git a/resource/schema/userdata.sql b/resource/schema/userdata.sql
index 42ba4f2ee4..6068fc3e45 100644
--- a/resource/schema/userdata.sql
+++ b/resource/schema/userdata.sql
@@ -1,4 +1,4 @@
--- 108
+-- 109
 
 -- Copyright (c) 2009 Center for History and New Media
 --                    George Mason University, Fairfax, Virginia, USA
@@ -456,4 +456,8 @@ CREATE TABLE translatorCache (
     fileName TEXT PRIMARY KEY,
     metadataJSON TEXT,
     lastModifiedTime INT
-);
\ No newline at end of file
+);
+
+CREATE TABLE dbDebug1 (
+    a INTEGER PRIMARY KEY
+);