diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1b07a4ee..fd910167 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,8 +24,9 @@ Expected: October 2024
 
 Users may have to change how they access the system
 
+* NETCONF error returns of failed leafref references, see https://github.com/clicon/clixon/issues/536
 * List pagination of large lists
-  * For backward-compatibility, mark the list with extension cl:list_pagination_partial_state extension
+  * For backward-compatibility, mark the list with extension cl:list-pagination-partial-state extension
   * New default is to use regular state read mechanism, which could have poorer performance but more functionality
 
 ### C/CLI-API changes on existing features
@@ -37,6 +38,10 @@ Developers may need to change their code
   * Replace `y1 = NULL; y1 = yn_each(y0, y1)` with `int inext = 0; yn_iter(y0, &inext)`
 * Add `keyw`argument to `yang_stats()`
 
+### Corrected Busg
+
+* Fixed: [NETCONF error reply from failed leafref rquire-instance does not comply to RFC 7950](https://github.com/clicon/clixon/issues/536)
+
 ## 7.1.0
 3 July 2024
 
diff --git a/lib/clixon/clixon_netconf_lib.h b/lib/clixon/clixon_netconf_lib.h
index d87d11b2..fdcceb50 100644
--- a/lib/clixon/clixon_netconf_lib.h
+++ b/lib/clixon/clixon_netconf_lib.h
@@ -162,6 +162,7 @@ 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);
 int netconf_missing_element(cbuf *cb, char *type, char *element, char *message);
+int netconf_missing_yang_xml(cxobj **xret, char *path, char *app_tag, char *info, char *message);
 int netconf_missing_element_xml(cxobj **xret, char *type, char *element, char *message);
 int netconf_bad_element(cbuf *cb, char *type, char *info, char *element);
 int netconf_bad_element_xml(cxobj **xret, char *type, char *info, char *element);
diff --git a/lib/src/clixon_netconf_lib.c b/lib/src/clixon_netconf_lib.c
index c2d91922..e089b4a1 100644
--- a/lib/src/clixon_netconf_lib.c
+++ b/lib/src/clixon_netconf_lib.c
@@ -1060,32 +1060,30 @@ netconf_data_missing_xml(cxobj **xret,
     return retval;
 }
 
-/*! Create Netconf data-missing / missing-choice as defeind in RFC 7950 15.6
+/*! Create Netconf data-missing / missing-choice as defined in RFC 7950 15.5/15.6
  *
- * If a NETCONF operation would result in configuration data where no
- * nodes exists in a mandatory choice, the following error MUST be
- * returned:
- * @param[out] xret       Error XML tree. Free with xml_free after use
- * @param[in]  x          Element with missing choice
- * @param[in]  name       Name of missing mandatory choice   
- * @param[in]  message    Error message
- * @retval     0       OK
- * @retval    -1       Error
+ * @param[out] xret     Error XML tree. Free with xml_free after use
+ * @param[in]  path     Path
+ * @param[in]  app-tag  Error app-tag
+ * @param[in]  info     Error info
+ * @param[in]  message  Error message
+ * @retval     0        OK
+ * @retval    -1        Error
  */
 int
-netconf_missing_choice_xml(cxobj **xret,
-                           cxobj  *x,
-                           char   *name,
-                           char   *message)
+netconf_missing_yang_xml(cxobj **xret,
+                         char   *path,
+                         char   *app_tag,
+                         char   *info,
+                         char   *message)
 {
     int    retval = -1;
     char  *encstr = NULL;
     cxobj *xerr;
-    char  *path = NULL;
     char  *encpath = NULL;
 
-    if (xret == NULL || name == NULL){
-        clixon_err(OE_NETCONF, EINVAL, "xret or name is NULL");
+    if (xret == NULL || path == NULL){
+        clixon_err(OE_NETCONF, EINVAL, "xret or path is NULL");
         goto done;      
     }
     if (*xret == NULL){
@@ -1098,21 +1096,23 @@ netconf_missing_choice_xml(cxobj **xret,
         goto done;
     if ((xerr = xml_new("rpc-error", *xret, CX_ELMNT)) == NULL)
         goto done;
-    /* error-path:     Path to the element with the missing choice. */
-    if (xml2xpath(x, NULL, 0, 0, &path) < 0)
-        goto done;
     if (xml_chardata_encode(&encpath, 0, "%s", path) < 0)
         goto done;
     if (clixon_xml_parse_va(YB_NONE, NULL, &xerr, NULL, 
                             "<error-type>application</error-type>"
                             "<error-tag>data-missing</error-tag>"
-                            "<error-app-tag>missing-choice</error-app-tag>"
-                            "<error-path>%s</error-path>"
-                            "<error-info><missing-choice xmlns=\"%s\">%s</missing-choice></error-info>"
-                            "<error-severity>error</error-severity>",
-                            encpath,
-                            YANG_XML_NAMESPACE,
-                            name) < 0)
+                            "<error-app-tag>%s</error-app-tag>"
+                            "<error-path>%s</error-path>",
+                            app_tag,
+                            encpath) < 0)
+        goto done;
+    if (info) {
+        if (clixon_xml_parse_va(YB_NONE, NULL, &xerr, NULL,
+                                "<error-info>%s</error-info>", info) < 0)
+            goto done;
+    }
+    if (clixon_xml_parse_va(YB_NONE, NULL, &xerr, NULL,
+                            "<error-severity>error</error-severity>") < 0)
         goto done;
     if (message){
         if (xml_chardata_encode(&encstr, 0, "%s", message) < 0)
@@ -1123,8 +1123,6 @@ netconf_missing_choice_xml(cxobj **xret,
     }
     retval = 0;
  done:
-    if (path)
-        free(path);
     if (encstr)
         free(encstr);
     if (encpath)
@@ -1132,6 +1130,52 @@ netconf_missing_choice_xml(cxobj **xret,
     return retval;
 }
 
+/*! Create Netconf data-missing / missing-choice as defined in RFC 7950 15.6
+ *
+ * If a NETCONF operation would result in configuration data where no
+ * nodes exists in a mandatory choice, the following error MUST be
+ * returned:
+ * @param[out] xret       Error XML tree. Free with xml_free after use
+ * @param[in]  x          Element with missing choice
+ * @param[in]  name       Name of missing mandatory choice
+ * @param[in]  message    Error message
+ * @retval     0       OK
+ * @retval    -1       Error
+ */
+
+int
+netconf_missing_choice_xml(cxobj **xret,
+                           cxobj  *x,
+                           char   *name,
+                           char   *message)
+{
+    int    retval = -1;
+    cbuf  *cbinfo = NULL;
+    char  *path = NULL;
+
+    if (name == NULL){
+        clixon_err(OE_NETCONF, EINVAL, "xret or name is NULL");
+        goto done;
+    }
+    /* error-path:  Path to the element. */
+    if (xml2xpath(x, NULL, 0, 0, &path) < 0)
+        goto done;
+    if ((cbinfo = cbuf_new()) == NULL){
+        clixon_err(OE_UNIX, errno, "cbuf_new");
+        goto done;
+    }
+    cprintf(cbinfo, "<missing-choice xmlns=\"%s\">%s</missing-choice>", YANG_XML_NAMESPACE, name);
+    if (netconf_missing_yang_xml(xret, path, "missing-choice", cbuf_get(cbinfo), message) < 0)
+        goto done;
+    retval = 0;
+ done:
+    if (path)
+        free(path);
+    if (cbinfo)
+        cbuf_free(cbinfo);
+    return retval;
+}
+
 /*! Create Netconf operation-not-supported error XML according to RFC 6241 App A
  *
  * Request could not be completed because the requested operation is not
diff --git a/lib/src/clixon_validate.c b/lib/src/clixon_validate.c
index bc62b38d..e6192797 100644
--- a/lib/src/clixon_validate.c
+++ b/lib/src/clixon_validate.c
@@ -133,7 +133,6 @@ validate_leafref(cxobj     *xt,
     cvec        *nsc = NULL;
     cbuf        *cberr = NULL;
     char        *path_arg;
-    yang_stmt   *ymod;
     cg_var      *cv;
     int          require_instance = 1;
 
@@ -179,13 +178,12 @@ validate_leafref(cxobj     *xt,
             clixon_err(OE_UNIX, errno, "cbuf_new");
             goto done;
         }
-        ymod = ys_module(ys);
-        cprintf(cberr, "Leafref validation failed: No leaf %s matching path %s in %s.yang:%d",
-                leafrefbody,
-                path_arg,
-                yang_argument_get(ymod),
-                yang_linenum_get(ys));
-        if (xret && netconf_bad_element_xml(xret, "application", leafrefbody, cbuf_get(cberr)) < 0)
+        /* RFC 7950 15.5 requires:
+           error-tag:      data-missing
+           error-app-tag:  instance-required
+           error-path:     Path to the instance-identifier or leafref leaf.
+         */
+        if (xret && netconf_missing_yang_xml(xret, path_arg, "instance-required", leafrefbody, NULL) < 0)
             goto done;
         goto fail;
     }
diff --git a/test/test_autocli_grouping.sh b/test/test_autocli_grouping.sh
index 7b834d08..f8646a5f 100755
--- a/test/test_autocli_grouping.sh
+++ b/test/test_autocli_grouping.sh
@@ -243,7 +243,7 @@ EOF
     expectpart "$($clixon_cli -f $cfg -1 set table parameter x index1 a scope 43)" 0 ""
     
     new "validate expect fail"
-    expectpart "$($clixon_cli -f $cfg -1 validate 2>&1)" 255 "bad-element Leafref validation failed: No leaf 43 matching path"
+    expectpart "$($clixon_cli -f $cfg -1 validate 2>&1)" 255 "data-missing" "instance-required : ../../value0"
 
     new "set leafref expect fail"
     expectpart "$($clixon_cli -f $cfg -1 set table parameter x value0 43)" 0 ""
diff --git a/test/test_cli_leafref.sh b/test/test_cli_leafref.sh
index 886e2d55..1e8a92d5 100755
--- a/test/test_cli_leafref.sh
+++ b/test/test_cli_leafref.sh
@@ -288,7 +288,7 @@ new "set leafref require-instance 99 (non-existent)"
 expectpart "$($clixon_cli -1 -f $cfg set leafrefsreqinst leafref 99)" 0 "^"$
 
 new "cli validate expect failure"
-expectpart "$($clixon_cli -1 -f $cfg -l o validate)" 255 "Leafref validation failed: No leaf 99 matching path"
+expectpart "$($clixon_cli -1 -f $cfg -l o validate)" 255 "data-missing 99: instance-required : /table/parameter/name"
 
 new "cli discard"
 expectpart "$($clixon_cli -1 -f $cfg -l o discard)" 0 ""
diff --git a/test/test_leafref.sh b/test/test_leafref.sh
index 7c00fb55..512af586 100755
--- a/test/test_leafref.sh
+++ b/test/test_leafref.sh
@@ -145,7 +145,8 @@ new "leafref add non-existing ref"
 expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><edit-config><target><candidate/></target><config><default-address xmlns=\"urn:example:clixon\"><absname>eth3</absname><address>10.0.4.6</address></default-address></config></edit-config></rpc>" "" "<rpc-reply $DEFAULTNS><ok/></rpc-reply>"
 
 new "leafref validate"
-expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><validate><source><candidate/></source></validate></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>bad-element</error-tag><error-info><bad-element>eth3</bad-element></error-info><error-severity>error</error-severity><error-message>Leafref validation failed: No leaf eth3 matching path /if:interfaces/if:interface/if:name in example.yang:[0-9]*</error-message></rpc-error></rpc-reply>" ""
+expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><validate><source><candidate/></source></validate></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-typ
+e><error-tag>data-missing</error-tag><error-app-tag>instance-required</error-app-tag><error-path>/if:interfaces/if:interface/if:name</error-path><error-info>eth3</error-info><error-severity>error</error-severity></rpc-error></rpc-reply>" ""
 
 #new "leafref wrong ref"
 #expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><edit-config><target><candidate/></target><config><default-address xmlns=\"urn:example:clixon\"><wrong>eth3</wrong><address>10.0.4.6</address></default-address></config></edit-config></rpc>" "" "<rpc-reply $DEFAULTNS><ok/></rpc-reply>"
@@ -175,7 +176,7 @@ new "leafref delete leaf"
 expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><edit-config><target><candidate/></target><config><interfaces xmlns=\"urn:ietf:params:xml:ns:yang:ietf-interfaces\" xmlns:nc=\"${BASENS}\"><interface nc:operation=\"delete\"><name>eth0</name></interface></interfaces></config></edit-config></rpc>" "" "<rpc-reply $DEFAULTNS><ok/></rpc-reply>"
 
 new "leafref validate (should fail)"
-expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><validate><source><candidate/></source></validate></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>bad-element</error-tag><error-info><bad-element>eth0</bad-element></error-info><error-severity>error</error-severity><error-message>Leafref validation failed: No leaf eth0 matching path /if:interfaces/if:interface/if:name in example.yang:[0-9]*</error-message></rpc-error></rpc-reply>" ""
+expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><validate><source><candidate/></source></validate></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>data-missing</error-tag><error-app-tag>instance-required</error-app-tag><error-path>/if:interfaces/if:interface/if:name</error-path><error-info>eth0</error-info><error-severity>error</error-severity></rpc-error></rpc-reply>" ""
 
 new "leafref discard-changes"
 expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><discard-changes/></rpc>" "" "<rpc-reply $DEFAULTNS><ok/></rpc-reply>"
diff --git a/test/test_leafref_augment.sh b/test/test_leafref_augment.sh
index afe93c64..5866df82 100755
--- a/test/test_leafref_augment.sh
+++ b/test/test_leafref_augment.sh
@@ -211,7 +211,7 @@ new "leafref augment+leafref config wrong ref"
 expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><edit-config><target><candidate/></target><config>$XML</config></edit-config></rpc>" "" "<rpc-reply $DEFAULTNS><ok/></rpc-reply>"
 
 new "leafref augment+leafref validate wrong ref"
-expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><validate><source><candidate/></source></validate></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>bad-element</error-tag><error-info><bad-element>xxx</bad-element></error-info><error-severity>error</error-severity><error-message>Leafref validation failed: No leaf xxx matching path /ex:sender/ex:name in augment.yang:[0-9]*</error-message></rpc-error></rpc-reply>" ""
+expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><validate><source><candidate/></source></validate></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>data-missing</error-tag><error-app-tag>instance-required</error-app-tag><error-path>/ex:sender/ex:name</error-path><error-info>xxx</error-info><error-severity>error</error-severity></rpc-error></rpc-reply>" ""
 
 new "netconf discard-changes"
 expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><discard-changes/></rpc>" "" "<rpc-reply $DEFAULTNS><ok/></rpc-reply>"
diff --git a/test/test_leafref_state.sh b/test/test_leafref_state.sh
index 842f0ad0..dfbbfcdf 100755
--- a/test/test_leafref_state.sh
+++ b/test/test_leafref_state.sh
@@ -202,10 +202,10 @@ expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS>
 
 # Leafref wrong internal: state references x but config contains only y
 new "netconf get / config+state should fail"
-expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><get content=\"all\"><filter type=\"xpath\" select=\"/\"/></get></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>operation-failed</error-tag><error-info><bad-element>x</bad-element></error-info><error-severity>error</error-severity><error-message>Leafref validation failed: No leaf x matching path /ex:sender-config/ex:name in leafref.yang:[0-9]*. Internal error, state callback returned invalid XML</error-message></rpc-error></rpc-reply>" ""
+expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><get content=\"all\"><filter type=\"xpath\" select=\"/\"/></get></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>operation-failed</error-tag><error-app-tag>instance-required</error-app-tag><error-path>/ex:sender-config/ex:name</error-path><error-info>x</error-info><error-severity>error</error-severity></rpc-error></rpc-reply>" ""
 
 new "netconf get / state-only should fail"
-expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><get content=\"nonconfig\"><filter type=\"xpath\" select=\"/\"/></get></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>operation-failed</error-tag><error-info><bad-element>x</bad-element></error-info><error-severity>error</error-severity><error-message>Leafref validation failed: No leaf x matching path /ex:sender-config/ex:name in leafref.yang:[0-9]*. Internal error, state callback returned invalid XML</error-message></rpc-error></rpc-reply>" ""
+expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><get content=\"nonconfig\"><filter type=\"xpath\" select=\"/\"/></get></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>operation-failed</error-tag><error-app-tag>instance-required</error-app-tag><error-path>/ex:sender-config/ex:name</error-path><error-info>x</error-info><error-severity>error</error-severity></rpc-error></rpc-reply>" ""
 
 new "netconf get / config-only ok"
 expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><get content=\"config\"><filter type=\"xpath\" select=\"/\"/></get></rpc>" "" "<rpc-reply $DEFAULTNS><data><sender-config xmlns=\"urn:example:example\"><name>y</name></sender-config></data></rpc-reply>"
diff --git a/test/test_leafref_union.sh b/test/test_leafref_union.sh
index f72ecd8f..1100d65e 100755
--- a/test/test_leafref_union.sh
+++ b/test/test_leafref_union.sh
@@ -150,7 +150,7 @@ new "netconf set union 66"
 expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><edit-config><target><candidate/></target><config><c xmlns=\"urn:example:clixon\"><z>66</z></c></config><default-operation>none</default-operation></edit-config></rpc>" "" "<rpc-reply $DEFAULTNS><ok/></rpc-reply>"
 
 new "netconf validate not ok"
-expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><validate><source><candidate/></source></validate></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>bad-element</error-tag><error-info><bad-element>66</bad-element></error-info><error-severity>error</error-severity><error-message>Leafref validation failed: No leaf 66 matching path ../y" ""
+expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><validate><source><candidate/></source></validate></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>data-missing</error-tag><error-app-tag>instance-required</error-app-tag><error-path>../y</error-path><error-info>66</error-info><error-severity>error</error-severity></rpc-error></rpc-reply>"
 
 new "netconf discard-changes"
 expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><discard-changes/></rpc>]]>]]>" "" "<rpc-reply $DEFAULTNS><ok/></rpc-reply>"
@@ -186,7 +186,7 @@ new "netconf set union 99"
 expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><edit-config><target><candidate/></target><config><c xmlns=\"urn:example:clixon\"><u>99</u></c></config><default-operation>none</default-operation></edit-config></rpc>" "" "<rpc-reply $DEFAULTNS><ok/></rpc-reply>"
 
 new "netconf validate not ok"
-expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><validate><source><candidate/></source></validate></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>bad-element</error-tag><error-info><bad-element>99</bad-element></error-info><error-severity>error</error-severity><error-message>Leafref validation failed" ""
+expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" "<rpc $DEFAULTNS><validate><source><candidate/></source></validate></rpc>" "<rpc-reply $DEFAULTNS><rpc-error><error-type>application</error-type><error-tag>data-missing</error-tag><error-app-tag>instance-required</error-app-tag><error-path>../x</error-path><error-info>99</error-info><error-severity>error</error-severity></rpc-error></rpc-reply>" ""
 
 if [ $BE -ne 0 ]; then
     new "Kill backend"