diff --git a/gateway-provider-security-pac4j/src/main/java/org/apache/hadoop/gateway/pac4j/session/KnoxSessionStore.java b/gateway-provider-security-pac4j/src/main/java/org/apache/hadoop/gateway/pac4j/session/KnoxSessionStore.java
index 24b6b6b..d1d4523 100644
--- a/gateway-provider-security-pac4j/src/main/java/org/apache/hadoop/gateway/pac4j/session/KnoxSessionStore.java
+++ b/gateway-provider-security-pac4j/src/main/java/org/apache/hadoop/gateway/pac4j/session/KnoxSessionStore.java
@@ -92,7 +92,7 @@
     }
 
     private String encryptBase64(final Object o) {
-        if (o == null) {
+        if (o == null || o.equals("")) {
             return null;
         } else {
             final byte[] bytes = javaSerializationHelper.serializeToBytes((Serializable) o);