--- a/AbstractSourceCodeManager.st	Mon Mar 21 06:42:17 2016 +0100
+++ b/AbstractSourceCodeManager.st	Thu Mar 24 07:05:38 2016 +0100
@@ -522,7 +522,7 @@
 
     extensionsRevisionInfo := self revisionInfoFromString:extensionsRevisionString inClass:nil.
     extensionsRevisionInfo isNil ifTrue:[
-        self halt:'oops - possibly corrupted extensions version string'.
+        self halt:('oops - possibly corrupted extensions version string: "%1" in class %2' bindWith:extensionsRevisionString with:defClass name).
         "/ check for umlaut-remover/adder bug from felix in extensionsRevisionString !!!!!!!!
         ^ self streamForClass:nil fileName:fileName revision:nil directory:dir module:mod cache:false.
     ].