diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52ae4212..dcdc822c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -57,6 +57,10 @@ Expected: June 2021
 
 Users may have to change how they access the system
 
+* Netconf message-id attribute changed from optional to mandatory
+  * Made NETCONF message handling more strict according to RFC 6241
+  * Set `CLICON_NETCONF_MESSAGE_ID_OPTIONAL` to true to accept omission of message-id attribute
+  * See also [need make sure message-id exist in rpc validate #240](https://github.com/clicon/clixon/issues/240)
 * Changed config and install options for Restconf
   * clixon_restconf daemon is installed in /usr/local/sbin (as clixon_backend), instead of /www-data
     * `configure --with-wwwdir=<dir>` remains but only applies to fcgi socket and log
@@ -64,11 +68,13 @@ Users may have to change how they access the system
   * Restconf drop privileges user is defined by `CLICON_RESTCONF_USER`
     * `configure --with-wwwuser=<user>` is removed
   * clixon_restconf drop of privileges is defined by `CLICON_RESTCONF_PRIVILEGES` option
-* New clixon-config@2020-05-20.yang revision
+* New clixon-config@2021-05-20.yang revision
   * Added: `CLICON_RESTCONF_USER`
   * Added: `CLICON_RESTCONF_PRIVILEGES`
   * Added: `CLICON_RESTCONF_INSTALLDIR`
+  * Added: `CLICON_RESTCONF_STARTUP_DONTUPDATE`
   * Added: `CLICON_RESTCONF_STARTUP_DONTUPDATE`	
+  * Added: `CLICON_NETCONF_MESSAGE_ID_OPTIONAL`
 * New clixon-restconf@2020-05-20.yang revision
   * Added: restconf `log-destination` 
 * RESTCONF error replies have changed
@@ -110,7 +116,9 @@ Developers may need to change their code
 	
 ### Corrected Bugs
 
-* Fixed: [ restconf patch method unable to chage value to empty string #229](https://github.com/clicon/clixon/issues/229)
+* Fixed: [need make sure message-id exist in rpc validate #240](https://github.com/clicon/clixon/issues/240)
+  * Netconf message-id attribute changed from optional to mandatory (see API changes)
+* Fixed: [restconf patch method unable to chage value to empty string #229](https://github.com/clicon/clixon/issues/229)
 * Fixed: [restconf patch method adds redundant namespaces #235](https://github.com/clicon/clixon/issues/235)
 * Fixed: Restconf HEAD did not work everywhere GET did, such as well-known and exact root.
 * Fixed: [JSON parsing error for a specific input. #236](https://github.com/clicon/clixon/issues/236)
diff --git a/apps/backend/backend_main.c b/apps/backend/backend_main.c
index 36494aff..9c10bd16 100644
--- a/apps/backend/backend_main.c
+++ b/apps/backend/backend_main.c
@@ -747,11 +747,6 @@ main(int    argc,
 		   clicon_configfile(h));
 	goto done;
     }
-
-    /* Treat unknown XML as anydata */
-    if (clicon_option_bool(h, "CLICON_YANG_UNKNOWN_ANYDATA") == 1)
-	xml_bind_yang_unknown_anydata(1);
-
     /* Publish stream on pubsub channels.
      * CLICON_STREAM_PUB should be set to URL to where streams are published
      * and configure should be run with --enable-publish
diff --git a/apps/cli/cli_main.c b/apps/cli/cli_main.c
index a78a128b..e965868f 100644
--- a/apps/cli/cli_main.c
+++ b/apps/cli/cli_main.c
@@ -635,11 +635,6 @@ main(int    argc,
 	goto done;
     /* Set default namespace according to CLICON_NAMESPACE_NETCONF_DEFAULT */
     xml_nsctx_namespace_netconf_default(h);
-    
-    /* Treat unknwon XML as anydata */
-    if (clicon_option_bool(h, "CLICON_YANG_UNKNOWN_ANYDATA") == 1)
-	xml_bind_yang_unknown_anydata(1);
-
     /* Create top-level and store as option */
     if ((yspec = yspec_new()) == NULL)
 	goto done;
diff --git a/apps/cli/cli_show.c b/apps/cli/cli_show.c
index 28947ea4..114f178b 100644
--- a/apps/cli/cli_show.c
+++ b/apps/cli/cli_show.c
@@ -495,8 +495,8 @@ cli_show_config1(clicon_handle h,
 	    cli_xml2cli(xc, prefix, gt, cligen_output); /* cli syntax */
 	break;
     case FORMAT_NETCONF:
-	cligen_output(stdout, "<rpc xmlns=\"%s\"><edit-config><target><candidate/></target><config>\n",
-		      NETCONF_BASE_NAMESPACE);
+	cligen_output(stdout, "<rpc xmlns=\"%s\" %s><edit-config><target><candidate/></target><config>\n",
+		      NETCONF_BASE_NAMESPACE, NETCONF_MESSAGE_ID_ATTR);
 	xc = NULL; /* Dont print xt itself */
 	while ((xc = xml_child_each(xt, xc, -1)) != NULL)
 	    cli_xml2file(xc, 2, 1, cligen_output);
diff --git a/apps/restconf/restconf_main_fcgi.c b/apps/restconf/restconf_main_fcgi.c
index 162f10c8..88622b6a 100644
--- a/apps/restconf/restconf_main_fcgi.c
+++ b/apps/restconf/restconf_main_fcgi.c
@@ -375,10 +375,6 @@ main(int    argc,
     if ((yspec = yspec_new()) == NULL)
 	goto done;
     clicon_dbspec_yang_set(h, yspec);
-    /* Treat unknown XML as anydata */
-    if (clicon_option_bool(h, "CLICON_YANG_UNKNOWN_ANYDATA") == 1)
-	xml_bind_yang_unknown_anydata(1);
-
     /* Initialize plugin module by creating a handle holding plugin and callback lists */
     if (clixon_plugin_module_init(h) < 0)
 	goto done;
diff --git a/apps/restconf/restconf_main_native.c b/apps/restconf/restconf_main_native.c
index 0a4532cb..ac89089a 100644
--- a/apps/restconf/restconf_main_native.c
+++ b/apps/restconf/restconf_main_native.c
@@ -1687,10 +1687,6 @@ restconf_clixon_init(clicon_handle h,
     if ((yspec = yspec_new()) == NULL)
 	goto done;
     clicon_dbspec_yang_set(h, yspec);
-    /* Treat unknown XML as anydata */
-    if (clicon_option_bool(h, "CLICON_YANG_UNKNOWN_ANYDATA") == 1)
-	xml_bind_yang_unknown_anydata(1);
-    
     /* Load restconf plugins before yangs are loaded (eg extension callbacks) */
     if ((dir = clicon_restconf_dir(h)) != NULL)
 	if (clixon_plugins_load(h, CLIXON_PLUGIN_INIT, dir, NULL) < 0)
diff --git a/apps/restconf/restconf_methods.c b/apps/restconf/restconf_methods.c
index 40d8fd99..10844869 100644
--- a/apps/restconf/restconf_methods.c
+++ b/apps/restconf/restconf_methods.c
@@ -513,11 +513,12 @@ api_data_write(clicon_handle h,
     /* Create text buffer for transfer to backend */
     if ((cbx = cbuf_new()) == NULL)
 	goto done;
-    cprintf(cbx, "<rpc xmlns=\"%s\" username=\"%s\" xmlns:%s=\"%s\">",
+    cprintf(cbx, "<rpc xmlns=\"%s\" username=\"%s\" xmlns:%s=\"%s\" %s>",
 	    NETCONF_BASE_NAMESPACE,
 	    username?username:"",
 	    NETCONF_BASE_PREFIX,
-	    NETCONF_BASE_NAMESPACE); /* bind nc to netconf namespace */
+	    NETCONF_BASE_NAMESPACE,  /* bind nc to netconf namespace */
+	    NETCONF_MESSAGE_ID_ATTR);
     cprintf(cbx, "<edit-config");
     /* RFC8040 Sec 1.4:
      * If this is a "data" request and the NETCONF server supports :startup,
@@ -753,11 +754,12 @@ api_data_delete(clicon_handle h,
     /* For internal XML protocol: add username attribute for access control
      */
     username = clicon_username_get(h);
-    cprintf(cbx, "<rpc xmlns=\"%s\" username=\"%s\" xmlns:%s=\"%s\">",
+    cprintf(cbx, "<rpc xmlns=\"%s\" username=\"%s\" xmlns:%s=\"%s\" %s>",
 	    NETCONF_BASE_NAMESPACE,
 	    username?username:"",
 	    NETCONF_BASE_PREFIX,
-	    NETCONF_BASE_NAMESPACE); /* bind nc to netconf namespace */
+	    NETCONF_BASE_NAMESPACE,
+	    NETCONF_MESSAGE_ID_ATTR); /* bind nc to netconf namespace */
 
     cprintf(cbx, "<edit-config");
     /* RFC8040 Sec 1.4:
diff --git a/apps/restconf/restconf_methods_post.c b/apps/restconf/restconf_methods_post.c
index 755f087f..bc0e2bfb 100644
--- a/apps/restconf/restconf_methods_post.c
+++ b/apps/restconf/restconf_methods_post.c
@@ -336,11 +336,12 @@ api_data_post(clicon_handle h,
     /* For internal XML protocol: add username attribute for access control
      */
     username = clicon_username_get(h);
-    cprintf(cbx, "<rpc xmlns=\"%s\" username=\"%s\" xmlns:%s=\"%s\">",
+    cprintf(cbx, "<rpc xmlns=\"%s\" username=\"%s\" xmlns:%s=\"%s\" %s>",
 	    NETCONF_BASE_NAMESPACE,
 	    username?username:"",
 	    NETCONF_BASE_PREFIX,
-	    NETCONF_BASE_NAMESPACE); /* bind nc to netconf namespace */
+	    NETCONF_BASE_NAMESPACE,
+	    NETCONF_MESSAGE_ID_ATTR); /* bind nc to netconf namespace */
 
     cprintf(cbx, "<edit-config");
     /* RFC8040 Sec 1.4:
@@ -755,13 +756,13 @@ api_operations_post(clicon_handle h,
      * <rpc username="foo"><myfn xmlns="uri"/>
      */
     if ((username = clicon_username_get(h)) != NULL){
-	if (clixon_xml_parse_va(YB_NONE, NULL, &xtop, NULL, "<rpc xmlns=\"%s\" username=\"%s\"/>",
-				NETCONF_BASE_NAMESPACE, username) < 0)
+	if (clixon_xml_parse_va(YB_NONE, NULL, &xtop, NULL, "<rpc xmlns=\"%s\" username=\"%s\" %s/>",
+				NETCONF_BASE_NAMESPACE, username, NETCONF_MESSAGE_ID_ATTR) < 0)
 	    goto done;
     }
     else
-	if (clixon_xml_parse_va(YB_NONE, NULL, &xtop, NULL, "<rpc xmlns=\"%s\"/>",
-				NETCONF_BASE_NAMESPACE) < 0)
+	if (clixon_xml_parse_va(YB_NONE, NULL, &xtop, NULL, "<rpc xmlns=\"%s\" %s/>",
+				NETCONF_BASE_NAMESPACE, NETCONF_MESSAGE_ID_ATTR) < 0)
 	    goto done;
     if (xml_rootchild(xtop, 0, &xtop) < 0)
 	goto done;
diff --git a/apps/restconf/restconf_stream_fcgi.c b/apps/restconf/restconf_stream_fcgi.c
index 680f8680..ddac456a 100644
--- a/apps/restconf/restconf_stream_fcgi.c
+++ b/apps/restconf/restconf_stream_fcgi.c
@@ -269,8 +269,8 @@ restconf_stream(clicon_handle h,
 	clicon_err(OE_XML, errno, "cbuf_new");
 	goto done;
     }
-    cprintf(cb, "<rpc xmlns=\"%s\"><create-subscription xmlns=\"%s\"><stream>%s</stream>",
-	    NETCONF_BASE_NAMESPACE, EVENT_RFC5277_NAMESPACE, name);
+    cprintf(cb, "<rpc xmlns=\"%s\" %s><create-subscription xmlns=\"%s\"><stream>%s</stream>",
+	    NETCONF_BASE_NAMESPACE, NETCONF_MESSAGE_ID_ATTR, EVENT_RFC5277_NAMESPACE, name);
     /* Print all fields */
     for (i=0; i<cvec_len(qvec); i++){
         cv = cvec_i(qvec, i);
diff --git a/lib/clixon/clixon_netconf_lib.h b/lib/clixon/clixon_netconf_lib.h
index deac778a..f42cf33d 100644
--- a/lib/clixon/clixon_netconf_lib.h
+++ b/lib/clixon/clixon_netconf_lib.h
@@ -52,6 +52,10 @@
 #define NETCONF_BASE_NAMESPACE "urn:ietf:params:xml:ns:netconf:base:1.0"
 #define NETCONF_BASE_PREFIX "nc"
 
+/* In cases where message-id is not given by external client, use this */
+#define NETCONF_MESSAGE_ID_DEFAULT "42"
+#define NETCONF_MESSAGE_ID_ATTR "message-id=\"42\""
+
 /* Netconf base capability as defined in RFC4741, Sec 8.1
  */
 #define NETCONF_BASE_CAPABILITY_1_0 "urn:ietf:params:netconf:base:1.0"
@@ -97,6 +101,7 @@ int netconf_invalid_value(cbuf *cb, char *type, char *message);
 int netconf_invalid_value_xml(cxobj **xret, char *type, char *message);
 int netconf_too_big(cbuf *cb, char *type, char *message);
 int netconf_missing_attribute(cbuf *cb,	char *type, char *info, char *message);
+int netconf_missing_attribute_xml(cxobj **xret, char *type, char *info, char *message);
 int netconf_bad_attribute(cbuf *cb, char *type, char *info, char *message);
 int netconf_bad_attribute_xml(cxobj **xret, char *type, char *info, char *message);
 int netconf_unknown_attribute(cbuf *cb,	char *type, char *info, char *message);
diff --git a/lib/clixon/clixon_xml_bind.h b/lib/clixon/clixon_xml_bind.h
index 73890bdf..ede4a63b 100644
--- a/lib/clixon/clixon_xml_bind.h
+++ b/lib/clixon/clixon_xml_bind.h
@@ -44,6 +44,7 @@
  * Prototypes
  */
 int xml_bind_yang_unknown_anydata(int val);
+int xml_bind_netconf_message_id_optional(int val);
 int xml_bind_yang_rpc(cxobj *xrpc, yang_stmt *yspec, cxobj **xerr);
 int xml_bind_yang_rpc_reply(cxobj *xrpc, char *name, yang_stmt *yspec, cxobj **xerr);
 int xml_bind_yang0(cxobj *xt, yang_bind yb, yang_stmt *yspec, cxobj **xerr);
diff --git a/lib/src/clixon_client.c b/lib/src/clixon_client.c
index 7701bf02..660ec422 100644
--- a/lib/src/clixon_client.c
+++ b/lib/src/clixon_client.c
@@ -170,9 +170,10 @@ clixon_client_lock(int         sock,
 	clicon_err(OE_PLUGIN, errno, "cbuf_new");
 	goto done;
     }
-    cprintf(msg, "<rpc xmlns=\"%s\">"
+    cprintf(msg, "<rpc xmlns=\"%s\" %s>"
 	    "<%slock><target><%s/></target></%slock></rpc>",
 	    NETCONF_BASE_NAMESPACE,
+	    NETCONF_MESSAGE_ID_ATTR,
 	    lock?"":"un", db, lock?"":"un");
     if (clicon_rpc1(sock, msg, msgret) < 0)
 	goto done;
@@ -422,6 +423,7 @@ clixon_client_get_xdata(int         sock,
     cprintf(msg, "<rpc xmlns=\"%s\"", NETCONF_BASE_NAMESPACE);
     cprintf(msg, " xmlns:%s=\"%s\"",
 	    NETCONF_BASE_PREFIX, NETCONF_BASE_NAMESPACE);
+    cprintf(msg, " %s", NETCONF_MESSAGE_ID_ATTR);
     cprintf(msg, "><get-config><source><%s/></source>", db);
     if (xpath && strlen(xpath)){
 	cprintf(msg, "<%s:filter %s:type=\"xpath\" xmlns=\"%s\" %s:select=\"%s\"",
diff --git a/lib/src/clixon_netconf_lib.c b/lib/src/clixon_netconf_lib.c
index d9be082a..febf5b93 100644
--- a/lib/src/clixon_netconf_lib.c
+++ b/lib/src/clixon_netconf_lib.c
@@ -65,6 +65,7 @@
 #include "clixon_xml.h"
 #include "clixon_options.h"
 #include "clixon_data.h"
+#include "clixon_xml_bind.h"
 #include "clixon_xml_map.h"
 #include "clixon_xml_io.h"
 #include "clixon_xpath_ctx.h"
@@ -228,44 +229,82 @@ netconf_too_big(cbuf *cb,
     goto done;
 }
 
+/*! Create Netconf missing-attribute error XML tree according to RFC 6241 App A
+ *
+ * An expected attribute is missing.
+ * @param[out] xret    Error XML tree. Free with xml_free after use
+ * @param[in]  type    Error type: "rpc", "application" or "protocol"
+ * @param[in]  attr    bad-attribute and/or bad-element xml
+ * @param[in]  message Error message (will be XML encoded)
+ */
+int
+netconf_missing_attribute_xml(cxobj **xret,
+			      char   *type,
+			      char   *attr,
+			      char   *message)
+{
+    int   retval = -1;
+    cxobj *xerr = NULL;
+    char  *encstr = NULL;
+    cxobj *xa;
+
+    if (*xret == NULL){
+	if ((*xret = xml_new("rpc-reply", NULL, CX_ELMNT)) == NULL)
+	    goto done;
+    }
+    else if (xml_name_set(*xret, "rpc-reply") < 0)
+	goto done;
+    if ((xa = xml_new("xmlns", *xret, CX_ATTR)) == NULL)
+	goto done;
+    if (xml_value_set(xa, NETCONF_BASE_NAMESPACE) < 0)
+	goto done;
+    if ((xerr = xml_new("rpc-error", *xret, CX_ELMNT)) == NULL)
+	goto done;
+    if (clixon_xml_parse_va(YB_NONE, NULL, &xerr, NULL, "<error-type>%s</error-type>"
+			    "<error-tag>missing-attribute</error-tag>"
+			    "<error-info><bad-attribute>%s</bad-attribute></error-info>"
+			    "<error-severity>error</error-severity>", type, attr) < 0)
+	goto done;
+    if (message){
+	if (xml_chardata_encode(&encstr, "%s", message) < 0)
+	    goto done;
+	if (clixon_xml_parse_va(YB_NONE, NULL, &xerr, NULL, "<error-message>%s</error-message>",
+				encstr) < 0)
+	    goto done;
+    }
+    retval = 0;
+ done:
+    if (encstr)
+	free(encstr);
+    return retval;
+}
+
 /*! Create Netconf missing-attribute error XML tree according to RFC 6241 App A
  *
  * An expected attribute is missing.
  * @param[out] cb      CLIgen buf. Error XML is written in this buffer
  * @param[in]  type    Error type: "rpc", "application" or "protocol"
- * @param[in]  info    bad-attribute or bad-element xml
- * @param[in]  message Error message (will be XML encoded)
+ * @param[in]  attr    bad-attribute 
+ * @param[in]  message Error message (will be XML encoded) or NULL
  */
 int
 netconf_missing_attribute(cbuf *cb,
 			  char *type,
-			  char *info,
+			  char *attr,
 			  char *message)
 {
-    int   retval = -1;
-    char *encstr = NULL;
+    int    retval = -1;
+    cxobj *xret = NULL;
 
-    if (cprintf(cb, "<rpc-reply xmlns=\"%s\"><rpc-error>"
-		"<error-type>%s</error-type>"
-		"<error-tag>missing-attribute</error-tag>"
-		"<error-info>%s</error-info>"
-		"<error-severity>error</error-severity>",
-		NETCONF_BASE_NAMESPACE,	type, info) <0)
-	goto err;
-    if (message){
-	if (xml_chardata_encode(&encstr, "%s", message) < 0)
-	    goto done;
-	if (cprintf(cb, "<error-message>%s</error-message>", encstr) < 0)
-	    goto err;
-    }
-    if (cprintf(cb, "</rpc-error></rpc-reply>") <0)
-	goto err;
+    if (netconf_missing_attribute_xml(&xret, type, attr, message) < 0)
+	goto done;
+    if (clicon_xml2cbuf(cb, xret, 0, 0, -1) < 0)
+	goto done;
     retval = 0;
  done:
+    if (xret)
+	xml_free(xret);
     return retval;
- err:
-    clicon_err(OE_XML, errno, "cprintf");
-    goto done;
 }
 
 /*! Create Netconf bad-attribute error XML tree according to RFC 6241 App A
@@ -1429,6 +1468,16 @@ netconf_module_load(clicon_handle h)
     /* Load restconf yang. Note this is also a part of clixon-config */
     if (yang_spec_parse_module(h, "clixon-restconf", NULL, yspec)< 0)
 	goto done;
+#if 1
+    /* XXX: Both the following settings are because clicon-handle is not part of all API
+     * functions
+     * Treat unknown XML as anydata */
+    if (clicon_option_bool(h, "CLICON_YANG_UNKNOWN_ANYDATA") == 1)
+	xml_bind_yang_unknown_anydata(1);
+    /* Make message-id attribute optional */
+    if (clicon_option_bool(h, "CLICON_NETCONF_MESSAGE_ID_OPTIONAL") == 1)
+	xml_bind_netconf_message_id_optional(1);
+#endif
     retval = 0;
  done:
     return retval;
diff --git a/lib/src/clixon_proto_client.c b/lib/src/clixon_proto_client.c
index fb22d5dc..c81a6ae7 100644
--- a/lib/src/clixon_proto_client.c
+++ b/lib/src/clixon_proto_client.c
@@ -451,6 +451,7 @@ clicon_rpc_get_config(clicon_handle h,
 	cprintf(cb, " username=\"%s\"", username);
     cprintf(cb, " xmlns:%s=\"%s\"",
 	    NETCONF_BASE_PREFIX, NETCONF_BASE_NAMESPACE);
+    cprintf(cb, " %s", NETCONF_MESSAGE_ID_ATTR);
     cprintf(cb, "><get-config><source><%s/></source>", db);
     if (xpath && strlen(xpath)){
 	cprintf(cb, "<%s:filter %s:type=\"xpath\" %s:select=\"%s\"",
@@ -541,6 +542,7 @@ clicon_rpc_edit_config(clicon_handle       h,
     cprintf(cb, " xmlns:%s=\"%s\"", NETCONF_BASE_PREFIX, NETCONF_BASE_NAMESPACE);
     if ((username = clicon_username_get(h)) != NULL)
 	cprintf(cb, " username=\"%s\"", username);
+    cprintf(cb, " %s", NETCONF_MESSAGE_ID_ATTR);
     cprintf(cb, "><edit-config><target><%s/></target>", db);
     cprintf(cb, "<default-operation>%s</default-operation>", 
 	    xml_operation2str(op));
@@ -595,10 +597,11 @@ clicon_rpc_copy_config(clicon_handle h,
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(session_id,
-				 "<rpc xmlns=\"%s\" username=\"%s\">"
+				 "<rpc xmlns=\"%s\" username=\"%s\" %s>"
 				 "<copy-config><source><%s/></source><target><%s/></target></copy-config></rpc>",
 				 NETCONF_BASE_NAMESPACE,
 				 username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR,
 				 db1, db2)) == NULL)
 	goto done;
     if (clicon_rpc_msg(h, msg, &xret) < 0)
@@ -641,10 +644,12 @@ clicon_rpc_delete_config(clicon_handle h,
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(session_id,
-				 "<rpc xmlns=\"%s\" username=\"%s\">"
+				 "<rpc xmlns=\"%s\" username=\"%s\" %s>"
 				 "<edit-config><target><%s/></target><default-operation>none</default-operation><config operation=\"delete\"/></edit-config></rpc>",
 				 NETCONF_BASE_NAMESPACE,
-				 username?username:"", db)) == NULL)
+				 username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR,
+				 db)) == NULL)
 	goto done;
     if (clicon_rpc_msg(h, msg, &xret) < 0)
 	goto done;
@@ -682,10 +687,12 @@ clicon_rpc_lock(clicon_handle h,
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(session_id,
-				 "<rpc xmlns=\"%s\" username=\"%s\">"
+				 "<rpc xmlns=\"%s\" username=\"%s\" %s>"
 				 "<lock><target><%s/></target></lock></rpc>",
 				 NETCONF_BASE_NAMESPACE,
-				 username?username:"", db)) == NULL)
+				 username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR,
+				 db)) == NULL)
 	goto done;
     if (clicon_rpc_msg(h, msg, &xret) < 0)
 	goto done;
@@ -723,10 +730,12 @@ clicon_rpc_unlock(clicon_handle h,
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(session_id,
-				 "<rpc xmlns=\"%s\" username=\"%s\">"
+				 "<rpc xmlns=\"%s\" username=\"%s\" %s>"
 				 "<unlock><target><%s/></target></unlock></rpc>",
 				 NETCONF_BASE_NAMESPACE,
-				 username?username:"", db)) == NULL)
+				 username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR,
+				 db)) == NULL)
 	goto done;
     if (clicon_rpc_msg(h, msg, &xret) < 0)
 	goto done;
@@ -805,6 +814,7 @@ clicon_rpc_get(clicon_handle   h,
 	cprintf(cb, " username=\"%s\"", username);
     cprintf(cb, " xmlns:%s=\"%s\"",
 	    NETCONF_BASE_PREFIX, NETCONF_BASE_NAMESPACE);
+    cprintf(cb, " %s", NETCONF_MESSAGE_ID_ATTR);
     cprintf(cb, "><get");
     /* Clixon extension, content=all,config, or nonconfig */
     if ((int)content != -1)
@@ -889,8 +899,9 @@ clicon_rpc_close_session(clicon_handle h)
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(session_id,
-				 "<rpc xmlns=\"%s\" username=\"%s\" message-id=\"%u\"><close-session/></rpc>",
-				 NETCONF_BASE_NAMESPACE, username?username:"", 42)) == NULL)
+				 "<rpc xmlns=\"%s\" username=\"%s\" %s><close-session/></rpc>",
+				 NETCONF_BASE_NAMESPACE, username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR)) == NULL)
 	goto done;
     if (clicon_rpc_msg(h, msg, &xret) < 0)
 	goto done;
@@ -932,9 +943,11 @@ clicon_rpc_kill_session(clicon_handle h,
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(my_session_id,
-				 "<rpc xmlns=\"%s\" username=\"%s\"><kill-session><session-id>%u</session-id></kill-session></rpc>",
+				 "<rpc xmlns=\"%s\" username=\"%s\" %s><kill-session><session-id>%u</session-id></kill-session></rpc>",
 				 NETCONF_BASE_NAMESPACE,
-				 username?username:"", session_id)) == NULL)
+				 username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR,
+				 session_id)) == NULL)
 	goto done;
     if (clicon_rpc_msg(h, msg, &xret) < 0)
 	goto done;
@@ -972,9 +985,11 @@ clicon_rpc_validate(clicon_handle h,
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(session_id,
-				 "<rpc xmlns=\"%s\" username=\"%s\"><validate><source><%s/></source></validate></rpc>",
+				 "<rpc xmlns=\"%s\" username=\"%s\" %s><validate><source><%s/></source></validate></rpc>",
 				 NETCONF_BASE_NAMESPACE,
-				 username?username:"", db)) == NULL)
+				 username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR,
+				 db)) == NULL)
 	goto done;
     if (clicon_rpc_msg(h, msg, &xret) < 0)
 	goto done;
@@ -1010,9 +1025,10 @@ clicon_rpc_commit(clicon_handle h)
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(session_id,
-				 "<rpc xmlns=\"%s\" username=\"%s\"><commit/></rpc>",
+				 "<rpc xmlns=\"%s\" username=\"%s\" %s><commit/></rpc>",
 				 NETCONF_BASE_NAMESPACE,
-				 username?username:"")) == NULL)
+				 username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR)) == NULL)
 	goto done;
     if (clicon_rpc_msg(h, msg, &xret) < 0)
 	goto done;
@@ -1048,9 +1064,10 @@ clicon_rpc_discard_changes(clicon_handle h)
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(session_id,
-				 "<rpc xmlns=\"%s\"  username=\"%s\"><discard-changes/></rpc>",
+				 "<rpc xmlns=\"%s\"  username=\"%s\" %s><discard-changes/></rpc>",
 				 NETCONF_BASE_NAMESPACE,
-				 username?username:"")) == NULL)
+				 username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR)) == NULL)
 	goto done;
     if (clicon_rpc_msg(h, msg, &xret) < 0)
 	goto done;
@@ -1094,12 +1111,13 @@ clicon_rpc_create_subscription(clicon_handle    h,
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(session_id,
-				 "<rpc xmlns=\"%s\" username=\"%s\"><create-subscription xmlns=\"%s\">"
+				 "<rpc xmlns=\"%s\" username=\"%s\" %s><create-subscription xmlns=\"%s\">"
 				 "<stream>%s</stream>"
 				 "<filter type=\"xpath\" select=\"%s\" />"
 				 "</create-subscription></rpc>", 
 				 NETCONF_BASE_NAMESPACE,
 				 username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR,
 				 EVENT_RFC5277_NAMESPACE,
 				 stream?stream:"", filter?filter:"")) == NULL)
 	goto done;
@@ -1139,9 +1157,10 @@ clicon_rpc_debug(clicon_handle h,
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(session_id,
-				 "<rpc xmlns=\"%s\" username=\"%s\"><debug xmlns=\"%s\"><level>%d</level></debug></rpc>",
+				 "<rpc xmlns=\"%s\" username=\"%s\" %s><debug xmlns=\"%s\"><level>%d</level></debug></rpc>",
 				 NETCONF_BASE_NAMESPACE,
 				 username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR,
 				 CLIXON_LIB_NS,
 				 level)) == NULL)
 	goto done;
@@ -1189,9 +1208,10 @@ clicon_rpc_restconf_debug(clicon_handle h,
 	goto done;
     username = clicon_username_get(h);
     if ((msg = clicon_msg_encode(session_id,
-				 "<rpc xmlns=\"%s\" username=\"%s\"><edit-config><target><candidate/></target><config><restconf xmlns=\"%s\"><debug>%d</debug></restconf></config></edit-config></rpc>",
+				 "<rpc xmlns=\"%s\" username=\"%s\" %s><edit-config><target><candidate/></target><config><restconf xmlns=\"%s\"><debug>%d</debug></restconf></config></edit-config></rpc>",
 				 NETCONF_BASE_NAMESPACE,
 				 username?username:"",
+				 NETCONF_MESSAGE_ID_ATTR,
 				 CLIXON_RESTCONF_NS,
 				 level)) == NULL)
 	goto done;
diff --git a/lib/src/clixon_xml_bind.c b/lib/src/clixon_xml_bind.c
index 35050cc5..7d38bff6 100644
--- a/lib/src/clixon_xml_bind.c
+++ b/lib/src/clixon_xml_bind.c
@@ -83,6 +83,7 @@
  * Local variables
  */
 static int _yang_unknown_anydata = 0;
+static int _netconf_message_id_optional = 0;
 
 /*! Kludge to equate unknown XML with anydata
  * The problem with this is that its global and should be bound to a handle
@@ -94,6 +95,16 @@ xml_bind_yang_unknown_anydata(int val)
     return 0;
 }
 
+/*! Kludge to set message_id_optional
+ * The problem with this is that its global and should be bound to a handle
+ */
+int
+xml_bind_netconf_message_id_optional(int val)
+{
+    _netconf_message_id_optional = val;
+    return 0;
+}
+
 /*! After yang binding, bodies of containers and lists are stripped from XML bodies
  * May apply to other nodes?
  */
@@ -510,16 +521,16 @@ xml_bind_yang0(cxobj     *xt,
  * @retval     -1      Error
  * The 
  * @code
- *   if (xml_bind_yang_rpc(h, x, NULL) < 0)
+ *   if (xml_bind_yang_rpc(x, NULL) < 0)
  *      err;
  * @endcode
  * @see xml_bind_yang  For other generic cases
  * @see xml_bind_yang_rpc_reply
  */
 int
-xml_bind_yang_rpc(cxobj     *xrpc,
-		  yang_stmt *yspec,
-		  cxobj    **xerr)
+xml_bind_yang_rpc(cxobj        *xrpc,
+		  yang_stmt    *yspec,
+		  cxobj       **xerr)
 {
     int        retval = -1;
     yang_stmt *yrpc = NULL;    /* yang node */
@@ -576,6 +587,17 @@ xml_bind_yang_rpc(cxobj     *xrpc,
 	    goto done;
 	goto fail;
     }
+    if (_netconf_message_id_optional == 0){
+	/* RFC 6241 4.1:
+	 *    The <rpc> element has a mandatory attribute "message-id"
+	 */
+	if (xml_find_type(xrpc, NULL, "message-id", CX_ATTR) == NULL){
+	    if (xerr &&
+		netconf_missing_attribute_xml(xerr, "rpc", "message-id", "Incoming rpc") < 0)
+		goto done;
+	    goto fail;
+	}
+    }
     x = NULL;
     while ((x = xml_child_each(xrpc, x, CX_ELMNT)) != NULL) {
 	rpcname = xml_name(x);
diff --git a/test/test_c++.sh b/test/test_c++.sh
index 497058e3..c9be6f2a 100755
--- a/test/test_c++.sh
+++ b/test/test_c++.sh
@@ -154,7 +154,7 @@ new "wait backend"
 wait_backend
 
 new "Netconf runtime test"
-expecteof "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO<rpc xmlns=\"urn:ietf:params:xml:ns:netconf:base:1.0\"><example xmlns=\"urn:example:clixon\"><x>0</x></example></rpc>]]>]]>" '^<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"><x xmlns="urn:example:clixon">0</x><y xmlns="urn:example:clixon">42</y></rpc-reply>]]>]]>$'
+expecteof "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><example xmlns=\"urn:example:clixon\"><x>0</x></example></rpc>]]>]]>" "^<rpc-reply $DEFAULTNS><x xmlns=\"urn:example:clixon\">0</x><y xmlns=\"urn:example:clixon\">42</y></rpc-reply>]]>]]>$"
 
 if [ $BE -ne 0 ]; then
    new "Kill backend"
diff --git a/test/test_client.sh b/test/test_client.sh
index 7a13092c..ed37410c 100755
--- a/test/test_client.sh
+++ b/test/test_client.sh
@@ -91,7 +91,7 @@ main(int    argc,
     /* Provide a clixon config-file, get a clixon handle */
     if ((h = clixon_client_init("$cfg")) == NULL)
        return -1;
-    /* Make a conenction over netconf or ssh/netconf */
+    /* Make a connection over netconf or ssh/netconf */
     if ((ch = clixon_client_connect(h, CLIXON_CLIENT_NETCONF)) == NULL)
        return -1;
 
diff --git a/test/test_nacm_module_read.sh b/test/test_nacm_module_read.sh
index 660308c0..80f2bb1c 100755
--- a/test/test_nacm_module_read.sh
+++ b/test/test_nacm_module_read.sh
@@ -232,13 +232,13 @@ new "limit rpc ok"
 expectpart "$(curl -u wilma:bar $CURLOPTS -X POST $RCPROTO://localhost/restconf/operations/clixon-example:example -H "Content-Type: application/yang-data+json" -d '{"clixon-example:input":{"x":42}}' )" 0 "HTTP/$HVER 200" '{"clixon-example:output":{"x":"42","y":"42"}}'
 
 new "limit rpc netconf ok"
-expecteof "$clixon_netconf -U wilma -qf $cfg" 0 "$DEFAULTHELLO<rpc xmlns=\"urn:ietf:params:xml:ns:netconf:base:1.0\"><example xmlns=\"urn:example:clixon\"><x>0</x></example></rpc>]]>]]>" '^<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"><x xmlns="urn:example:clixon">0</x><y xmlns="urn:example:clixon">42</y></rpc-reply>]]>]]>$'
+expecteof "$clixon_netconf -U wilma -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><example xmlns=\"urn:example:clixon\"><x>0</x></example></rpc>]]>]]>" "^<rpc-reply $DEFAULTNS><x xmlns=\"urn:example:clixon\">0</x><y xmlns=\"urn:example:clixon\">42</y></rpc-reply>]]>]]>$"
 
 new "guest rpc fail"
 expectpart "$(curl -u guest:bar $CURLOPTS -X POST $RCPROTO://localhost/restconf/operations/clixon-example:example -H "Content-Type: application/yang-data+json" -d '{"clixon-example:input":{"x":42}}' )" 0 "HTTP/$HVER 403" '{"ietf-restconf:errors":{"error":{"error-type":"application","error-tag":"access-denied","error-severity":"error","error-message":"access denied"}}}'
 
 new "guest rpc netconf fail"
-expecteof "$clixon_netconf -U guest -qf $cfg" 0 "$DEFAULTHELLO<rpc xmlns=\"urn:ietf:params:xml:ns:netconf:base:1.0\"><example xmlns=\"urn:example:clixon\"><x>0</x></example></rpc>]]>]]>" '^<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"><rpc-error><error-type>application</error-type><error-tag>access-denied</error-tag><error-severity>error</error-severity><error-message>access denied</error-message></rpc-error></rpc-reply>]]>]]>$'
+expecteof "$clixon_netconf -U guest -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><example xmlns=\"urn:example:clixon\"><x>0</x></example></rpc>]]>]]>" "^<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>access-denied</error-tag><error-severity>error</error-severity><error-message>access denied</error-message></rpc-error></rpc-reply>]]>]]>$"
 
 #------------------ Set read-default permit
 
diff --git a/test/test_netconf.sh b/test/test_netconf.sh
index dba65cf7..6339b0bc 100755
--- a/test/test_netconf.sh
+++ b/test/test_netconf.sh
@@ -26,6 +26,7 @@ cat <<EOF > $cfg
   <CLICON_BACKEND_DIR>/usr/local/lib/$APPNAME/backend</CLICON_BACKEND_DIR>
   <CLICON_BACKEND_REGEXP>example_backend.so$</CLICON_BACKEND_REGEXP>
   <CLICON_NETCONF_DIR>/usr/local/lib/$APPNAME/netconf</CLICON_NETCONF_DIR>
+  <CLICON_NETCONF_MESSAGE_ID_OPTIONAL>false</CLICON_NETCONF_MESSAGE_ID_OPTIONAL>
   <CLICON_RESTCONF_DIR>/usr/local/lib/$APPNAME/restconf</CLICON_RESTCONF_DIR>
   <CLICON_CLI_DIR>/usr/local/lib/$APPNAME/cli</CLICON_CLI_DIR>
   <CLICON_CLI_MODE>$APPNAME</CLICON_CLI_MODE>
@@ -67,6 +68,9 @@ expecteof "$clixon_netconf -qf $cfg" 0 "<hello $DEFAULTNS><capabilities><capabil
 new "Frame with unknown message"
 expecteof "$clixon_netconf -qf $cfg" 0 "<xxx $DEFAULTNS></xxx>]]>]]>" "^<rpc-reply $DEFAULTNS><rpc-error><error-type>protocol</error-type><error-tag>unknown-element</error-tag><error-info><bad-element>xxx</bad-element></error-info><error-severity>error</error-severity><error-message>Unrecognized netconf operation</error-message></rpc-error></rpc-reply>]]>]]>$"
 
+new "Frame without message-id attribute"
+expecteof "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTONLY><get-config><source><candidate/></source></get-config></rpc>]]>]]>" "^<rpc-reply $DEFAULTONLY><rpc-error><error-type>rpc</error-type><error-tag>missing-attribute</error-tag><error-info><bad-attribute>message-id</bad-attribute></error-info><error-severity>error</error-severity><error-message>Incoming rpc</error-message></rpc-error></rpc-reply>]]>]]>$"
+
 new "netconf rcv hello, disable RFC7895/ietf-yang-library"
 expecteof "$clixon_netconf -f $cfg -o CLICON_MODULE_LIBRARY_RFC7895=0" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><get-config><source><candidate/></source></get-config></rpc>]]>]]>" "^<hello $DEFAULTNS><capabilities><capability>urn:ietf:params:netconf:base:1.1</capability><capability>urn:ietf:params:netconf:base:1.0</capability><capability>urn:ietf:params:netconf:capability:candidate:1.0</capability><capability>urn:ietf:params:netconf:capability:validate:1.1</capability><capability>urn:ietf:params:netconf:capability:startup:1.0</capability><capability>urn:ietf:params:netconf:capability:xpath:1.0</capability><capability>urn:ietf:params:netconf:capability:notification:1.0</capability></capabilities><session-id>[0-9]*</session-id></hello>]]>]]><rpc-reply $DEFAULTNS><data/></rpc-reply>]]>]]>$"
 
diff --git a/test/test_restconf.sh b/test/test_restconf.sh
index 99b227ec..91df06ca 100755
--- a/test/test_restconf.sh
+++ b/test/test_restconf.sh
@@ -393,7 +393,7 @@ function testrun()
 
     new "restconf rpc using POST xml"
     ret=$(curl $CURLOPTS -X POST -H "Content-Type: application/yang-data+json" -H "Accept: application/yang-data+xml" -d '{"clixon-example:input":{"x":42}}' $proto://$addr/restconf/operations/clixon-example:example)
-    expect='<output xmlns="urn:example:clixon"><x>42</x><y>42</y></output>'
+    expect='<output message-id="42" xmlns="urn:example:clixon"><x>42</x><y>42</y></output>'
     match=`echo $ret | grep --null -Eo "$expect"`
     if [ -z "$match" ]; then
 	err "$expect" "$ret"
diff --git a/test/test_rpc.sh b/test/test_rpc.sh
index f0d61b17..9b8acd9c 100755
--- a/test/test_rpc.sh
+++ b/test/test_rpc.sh
@@ -89,10 +89,10 @@ new "restconf example rpc xml/json"
 expectpart "$(curl $CURLOPTS -X POST -H 'Content-Type: application/yang-data+xml' -H 'Accept: application/yang-data+json' -d '<input xmlns="urn:example:clixon"><x>0</x></input>' $RCPROTO://localhost/restconf/operations/clixon-example:example)"  0 'Content-Type: application/yang-data+json' '{"clixon-example:output":{"x":"0","y":"42"}}'
 
 new "restconf example rpc json/xml"
-expectpart "$(curl $CURLOPTS -X POST -H 'Content-Type: application/yang-data+json' -H 'Accept: application/yang-data+xml' -d '{"clixon-example:input":{"x":"0"}}' $RCPROTO://localhost/restconf/operations/clixon-example:example)" 0 'Content-Type: application/yang-data+xml' '<output xmlns="urn:example:clixon"><x>0</x><y>42</y></output>'
+expectpart "$(curl $CURLOPTS -X POST -H 'Content-Type: application/yang-data+json' -H 'Accept: application/yang-data+xml' -d '{"clixon-example:input":{"x":"0"}}' $RCPROTO://localhost/restconf/operations/clixon-example:example)" 0 'Content-Type: application/yang-data+xml' '<output message-id="42" xmlns="urn:example:clixon"><x>0</x><y>42</y></output>'
 
 new "restconf example rpc xml/xml"
-expectpart "$(curl $CURLOPTS -X POST -H 'Content-Type: application/yang-data+xml' -H 'Accept: application/yang-data+xml' -d '<input xmlns="urn:example:clixon"><x>0</x></input>' $RCPROTO://localhost/restconf/operations/clixon-example:example)" 0 'Content-Type: application/yang-data+xml' '<output xmlns="urn:example:clixon"><x>0</x><y>42</y></output>'
+expectpart "$(curl $CURLOPTS -X POST -H 'Content-Type: application/yang-data+xml' -H 'Accept: application/yang-data+xml' -d '<input xmlns="urn:example:clixon"><x>0</x></input>' $RCPROTO://localhost/restconf/operations/clixon-example:example)" 0 'Content-Type: application/yang-data+xml' '<output message-id="42" xmlns="urn:example:clixon"><x>0</x><y>42</y></output>'
 
 new "restconf example rpc xml in w json encoding (expect fail)"
 expectpart "$(curl $CURLOPTS -X POST -H 'Content-Type: application/yang-data+json' -H 'Accept: application/yang-data+xml' -d '<input xmlns="urn:example:clixon"><x>0</x></input>' $RCPROTO://localhost/restconf/operations/clixon-example:example)" 0 "HTTP/$HVER 400" "<errors xmlns=\"urn:ietf:params:xml:ns:yang:ietf-restconf\"><error><error-type>rpc</error-type><error-tag>malformed-message</error-tag><error-severity>error</error-severity><error-message>json_parse: line 1: syntax error at or before: '&lt;'</error-message></error></errors>"
diff --git a/yang/clixon/clixon-config@2021-05-20.yang b/yang/clixon/clixon-config@2021-05-20.yang
index 4a8cca7b..0e729594 100644
--- a/yang/clixon/clixon-config@2021-05-20.yang
+++ b/yang/clixon/clixon-config@2021-05-20.yang
@@ -50,6 +50,7 @@ module clixon-config {
 	            CLICON_RESTCONF_PRIVILEGES
 	            CLICON_RESTCONF_INSTALLDIR
 	            CLICON_RESTCONF_STARTUP_DONTUPDATE
+                    CLICON_NETCONF_MESSAGE_ID_OPTIONAL
              Released in Clixon 5.2";
     }
     revision 2021-03-08 {
@@ -465,6 +466,16 @@ module clixon-config {
                  is returned, which conforms to the RFC.
                  Note this applies only to external NETCONF, not the internal (IPC) netconf";
 	}
+	leaf CLICON_NETCONF_MESSAGE_ID_OPTIONAL {
+	    type boolean;
+	    default false;
+	    description
+		"This option relates to RFC 6241 Sec 4.1 <rpc> Element
+                 The <rpc> element has a mandatory attribute 'message-id', which is a
+                 string chosen by the sender of the RPC.
+                 If true, an RPC can be sent without a message-id.
+                 This applies to both  external NETCONF and internal (IPC) netconf";
+	}
 	leaf CLICON_RESTCONF_DIR {
 	    type string;
 	    description