src/HOL/Tools/ATP/atp_systems.ML

     (SOME sys, _) => sys
   | (NONE, []) => error ("SystemOnTPTP is not available.")
   | (NONE, syss) =>
     case syss |> filter_out (String.isPrefix "%")
               |> filter_out (curry (op =) "") of
-      [] => error ("SystemOnTPTP is not available.")
-    | [msg] => error ("SystemOnTPTP is not available: " ^ msg ^ ".")
+      [] => error ("SystemOnTPTP is currently not available.")
+    | [msg] => error ("SystemOnTPTP is currently not available: " ^ msg ^ ".")
     | syss =>
       error ("System " ^ quote name ^ " is not available at SystemOnTPTP.\n" ^
              "(Available systems: " ^ commas_quote syss ^ ".)")
 
 val max_remote_secs = 240 (* give Geoff Sutcliffe's servers a break *)