diff --git a/src/main/java/org/olat/shibboleth/ShibbolethModule.java b/src/main/java/org/olat/shibboleth/ShibbolethModule.java
index 8ac14536c0b7c299bfb57c700a941de62bf13694..5a8872dea0723264fbebab9fa9b5d0e8928dc956 100644
--- a/src/main/java/org/olat/shibboleth/ShibbolethModule.java
+++ b/src/main/java/org/olat/shibboleth/ShibbolethModule.java
@@ -174,9 +174,11 @@ public class ShibbolethModule extends AbstractSpringModule implements ConfigOnOf
 		List<String> keyStrings = Arrays.asList(raw.split(AUTHOR_CONTAINS_SPLIT_VALUE));
 		for (String keyString : keyStrings) {
 			try {
-				keys.add(IdentifierKey.valueOf(keyString));
+				if (StringHelper.containsNonWhitespace(keyString)) {
+					keys.add(IdentifierKey.valueOf(keyString));
+				}
 			} catch (Exception e) {
-				log.warn("The value '" + keyString + "' for the property 'shib.ac.auto.identifiers' is not valid.");
+				log.warn("The value '" + keyString + "' for the property 'method.auto.shib.identifiers' is not valid.");
 			}
 		}
 		return keys;