diff --git a/instana/meter.py b/instana/meter.py
index 15f235a0..8302ae83 100644
--- a/instana/meter.py
+++ b/instana/meter.py
@@ -247,7 +247,10 @@ def collect_snapshot(self):
     def jsonable(self, value):
         try:
             if callable(value):
-                result = value()
+                try:
+                    result = value()
+                except:
+                    result = 'Unknown'
             elif type(value) is ModuleType:
                 result = value
             else: