diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index e700782d3c..a4ce99ba4d 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7040,9 +7040,8 @@ local0.*    /var/log/postgresql
         The name will be displayed in the <structname>pg_stat_activity</structname> view
         and included in CSV log entries.  It can also be included in regular
         log entries via the <xref linkend="guc-log-line-prefix"/> parameter.
-        Only printable ASCII characters may be used in the
-        <varname>application_name</varname> value. Other characters will be
-        replaced with question marks (<literal>?</literal>).
+        Non-ASCII characters used in the <varname>application_name</varname>
+        will be replaced with hexadecimal strings.
        </para>
       </listitem>
      </varlistentry>
@@ -8037,10 +8036,9 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
        <para>
         The name can be any string of less
         than <symbol>NAMEDATALEN</symbol> characters (64 characters in a standard
-        build). Only printable ASCII characters may be used in the
-        <varname>cluster_name</varname> value. Other characters will be
-        replaced with question marks (<literal>?</literal>).  No name is shown
-        if this parameter is set to the empty string <literal>''</literal> (which is
+        build). Non-ASCII characters used in the <varname>cluster_name</varname>
+        will be replaced with hexadecimal strings. No name is shown if this
+        parameter is set to the empty string <literal>''</literal> (which is
         the default). This parameter can only be set at server start.
        </para>
       </listitem>
diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
index 5062d712e7..98785e87ea 100644
--- a/doc/src/sgml/postgres-fdw.sgml
+++ b/doc/src/sgml/postgres-fdw.sgml
@@ -1067,9 +1067,8 @@ postgres=# SELECT postgres_fdw_disconnect_all();
       of any length and contain even non-ASCII characters.  However when
       it's passed to and used as <varname>application_name</varname>
       in a foreign server, note that it will be truncated to less than
-      <symbol>NAMEDATALEN</symbol> characters and anything other than
-      printable ASCII characters will be replaced with question
-      marks (<literal>?</literal>).
+      <symbol>NAMEDATALEN</symbol> characters and non-ASCII characters will be
+      replaced with hexadecimal strings.
       See <xref linkend="guc-application-name"/> for details.
      </para>