event-impl/impl/src/java/org/sakaiproject/event/impl/UsageSessionServiceAdaptor.java
===================================================================
event-impl/impl/src/java/org/sakaiproject/event/impl/UsageSessionServiceAdaptor.java	(revision 42365)
event-impl/impl/src/java/org/sakaiproject/event/impl/UsageSessionServiceAdaptor.java	(working copy)
@@ -1080,7 +1080,7 @@
 			// and store it in the db
 			String statement = usageSessionServiceSql.getInsertSakaiSessionSql();
 
-			String userAgent = session.getUserAgent().length() > 255? session.getUserAgent().substring(0, 255) : session.getUserAgent();
+			String userAgent = session.getUserAgent() != null && session.getUserAgent().length() > 255? session.getUserAgent().substring(0, 255) : session.getUserAgent();
 
 			// process the insert
 			boolean ok = sqlService().dbWrite(statement, new Object[] {