diff --git a/backend.php b/backend.php
index 43b3b4290..44391c482 100644
--- a/backend.php
+++ b/backend.php
@@ -3912,6 +3912,10 @@
 			return "config: you have enabled DISABLE_SESSIONS. Please disable this option.";
 		}
 
+		if (DATABASE_BACKED_SESSIONS && SINGLE_USER_MODE) {
+			return "config: DATABASE_BACKED_SESSIONS is incompatible with SINGLE_USER_MODE";
+		}
+
 		return false;
 	}
 
diff --git a/tt-rss.js b/tt-rss.js
index 4c02a515f..08fdb945a 100644
--- a/tt-rss.js
+++ b/tt-rss.js
@@ -153,14 +153,14 @@ function backend_sanity_check_callback() {
 		try {
 		
 			if (!xmlhttp.responseXML) {
-				fatalError(3, "D001;" + xmlhttp.responseText);
+				fatalError(3, "D001: " + xmlhttp.responseText);
 				return;
 			}
 	
 			var reply = xmlhttp.responseXML.firstChild;
 	
 			if (!reply) {
-				fatalError(3, "D002;" + xmlhttp.responseText);
+				fatalError(3, "D002: " + xmlhttp.responseText);
 				return;
 			}