Index: openacs-4/packages/acs-authentication/tcl/authentication-procs-naviserver.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-authentication/tcl/authentication-procs-naviserver.tcl,v
diff -u -N -r1.5 -r1.5.2.1
--- openacs-4/packages/acs-authentication/tcl/authentication-procs-naviserver.tcl	5 Aug 2018 10:33:23 -0000	1.5
+++ openacs-4/packages/acs-authentication/tcl/authentication-procs-naviserver.tcl	14 Feb 2021 21:21:52 -0000	1.5.2.1
@@ -84,12 +84,13 @@
 
         #
         # In general we face here a race condition. The entry for the
-        # keys might have timed out before the collection of the
-        # content and now. So, the cache lookup might fail. So, we
-        # preset the "value" with a default in case the "ns_cache_get" fails.
+        # keys might have timed out. So, the cache lookup might
+        # fail. So, we provide a "value" with an empty string as
+        # default.
         #
-        set value ""
-        ns_cache_get ns:memoize $key value
+        if {![ns_cache_get ns:memoize $key value]} {
+            set value ""
+        }
 
         lappend result [string range $key 14 end] [ns_time seconds $expire] $value
     }