diff --git a/protocol.html b/protocol.html
index 5e143060..618c7ee2 100644
--- a/protocol.html
+++ b/protocol.html
@@ -712,6 +712,10 @@ <h3 property="schema:name">Writing Resources</h3>
 
 		  </p>
 
+		  <p>
+		    <span about="" id="server-patch-sparql-abort" rel="spec:requirement" resource="#server-patch-sparql-abort"><span property="spec:statement">If <span rel="spec:requirementSubject" resource="spec:Server">servers</span> that process SPARQL 1.1 Update’s [<cite><a class="bibref" href="#bib-sparql11-update">SPARQL11-UPDATE</a></cite>]) <code>DELETE/INSERT</code> operation finds any solution that produces a triple containing an unbound variable or an illegal RDF construct, then the server <span rel="spec:requirementLevel" resource="spec:MUST">MUST</span> abort any modifications and respond with a <code>409</code> status code.</span></span>
+		  </p>
+
 		  <p>
 		    <span about="" id="server-patch-sparql-insert" rel="spec:requirement" resource="#server-patch-sparql-insert"><span property="spec:statement">When the request body of a <code>PATCH</code> request has a SPARQL Update query that contains an <code>INSERT</code> keyword, <span rel="spec:requirementSubject" resource="spec:Server">servers</span> <span rel="spec:requirementLevel" resource="spec:MUST">MUST</span> treat the request as an <a href="#append-operation">Append operation</a>.</span></span>
 		    <span about="" id="server-patch-sparql-where" rel="spec:requirement" resource="#server-patch-sparql-where"><span property="spec:statement">When the query contains a <code>WHERE</code> keyword, <span rel="spec:requirementSubject" resource="spec:Server">servers</span> <span rel="spec:requirementLevel" resource="spec:MUST">MUST</span> treat the request as a <a href="#read-operation">Read operation</a>.</span></span>
@@ -1260,6 +1264,8 @@ <h3 property="schema:name">Normative References</h3>
                     <dd><a href="https://solid.github.io/solid-oidc/" rel="cito:citesAsAuthority"><cite>SOLID-OIDC</cite></a>. Aaron Coburn; elf Pavlik; Dmitri Zagidulin.  W3C Solid Community Group. W3C Editor's Draft. URL: <a href="https://solid.github.io/solid-oidc/">https://solid.github.io/solid-oidc/</a></dd>
                     <dt id="bib-sparql-overview">[SPARQL]</dt>
                     <dd><a href="https://www.w3.org/TR/sparql11-overview/" rel="cito:citesAsAuthority"><cite>SPARQL 1.1 Overview</cite></a>. The W3C SPARQL Working Group.  W3C. 21 March 2013. W3C Recommendation. URL: <a href="https://www.w3.org/TR/sparql11-overview/">https://www.w3.org/TR/sparql11-overview/</a></dd>
+                    <dt id="bib-sparql11-update">[SPARQL11-UPDATE]</dt>
+                    <dd><a href="https://www.w3.org/TR/sparql11-update/" rel="cito:citesAsAuthority"><cite>SPARQL 1.1 Update</cite></a>. Paula Gearon; Alexandre Passant; Axel Polleres.  W3C. 21 March 2013. W3C Recommendation. URL: <a href="https://www.w3.org/TR/sparql11-update/">https://www.w3.org/TR/sparql11-update/</a></dd>
                     <dt id="bib-turtle">[Turtle]</dt>
                     <dd><a href="https://www.w3.org/TR/turtle/" rel="cito:citesAsAuthority"><cite>RDF 1.1 Turtle</cite></a>. Eric Prud'hommeaux; Gavin Carothers.  W3C. 25 February 2014. W3C Recommendation. URL: <a href="https://www.w3.org/TR/turtle/">https://www.w3.org/TR/turtle/</a></dd>
                     <dt id="bib-w3c-html">[W3C-HTML]</dt>