diff --git a/xmpp_error.go b/xmpp_error.go
new file mode 100644
index 0000000..026820a
--- /dev/null
+++ b/xmpp_error.go
@@ -0,0 +1,57 @@
+package xmpp
+
+import (
+	"fmt"
+)
+
+// ErrorServiceUnavailable implements error response about feature that is not available. Currently implemented for
+// xep-0030.
+// QueryXmlns is about incoming xmlns attribute in query tag.
+// Node is about incoming node attribute in query tag (looks like it used only in disco#commands).
+//
+// If queried feature is not here on purpose, standards suggest answer with this stanza.
+func (c *Client) ErrorServiceUnavailable(v IQ, queryXmlns, node string) (string, error) {
+	query := fmt.Sprintf("<query xmlns=\"%s\" ", queryXmlns)
+
+	if node != "" {
+		query += fmt.Sprintf("node=\"%s\" />", node)
+	} else {
+		query += "/>"
+	}
+
+	query += "<error type=\"cancel\">"
+	query += "<service-unavailable xmlns=\"urn:ietf:params:xml:ns:xmpp-stanzas\" />"
+	query += "</error>"
+
+	return c.RawInformation(
+		v.To,
+		v.From,
+		v.ID,
+		IQTypeError,
+		query,
+	)
+}
+
+// ErrorNotImplemented implements error response about feature that is not (yet?) implemented.
+// Xmlns is about not implemented feature.
+//
+// If queried feature is not here because of it under development or for similar reasons, standards suggest answer with
+// this stanza.
+func (c *Client) ErrorNotImplemented(v IQ, xmlns, feature string) (string, error) {
+	query := "<error type=\"cancel\">"
+	query += "<feature-not-implemented xmlns=\"urn:ietf:params:xml:ns:xmpp-stanzas\" />"
+	query += fmt.Sprintf(
+		"<unsupported xmlns=\"%s\" feature=\"%s\" />",
+		xmlns,
+		feature,
+	)
+	query += "</error>"
+
+	return c.RawInformation(
+		v.To,
+		v.From,
+		v.ID,
+		IQTypeError,
+		query,
+	)
+}