diff -r 7a6301d01199 -r 4879d0021185 src/Pure/PIDE/protocol.ML
--- a/src/Pure/PIDE/protocol.ML	Sat Jun 25 09:50:40 2022 +0000
+++ b/src/Pure/PIDE/protocol.ML	Tue Jun 28 11:24:59 2022 +0200
@@ -24,7 +24,7 @@
        Isabelle_Process.init_options_interactive ()));
 
 val _ =
-  Protocol_Command.define "Prover.init_session"
+  Protocol_Command.define_bytes "Prover.init_session"
     (fn [yxml] => Resources.init_session_yxml yxml);
 
 val _ =