Hi Hynek Keycloak 3.3.0 Final is still broken for issue KEYCLOAK-4818. https://issues.jboss.org/browse/KEYCLOAK-4818 The SAML dsig error occurred in SAMLDataMarshaller.*deserialize()* method The fix for KEYCLOAK-4818 was added to SAMLDataMarshaller.*serialize()* method however the error occured in SAMLDataMarshaller.*deserialize()* method. Please refer to the change set report below. https://source.jboss.org/changelog/Keycloak?cs=d52d685161336 d68413bc633a81b223c66886c7a I also notice in the change set, the new unit test methods only assert the serialize() method. The deserialize() test method (ie *testParseResponse() ) does not test *for any dsig namespace. Are you able to update your unit test and verify the fix? Thank you for your help. SAMLDataMarshaller.java line 85 Caused by: java.lang.RuntimeException: com.ctc.wstx.exc.WstxParsingException: Undeclared namespace prefix "dsig" at [row,col {unknown-source}]: [1,914] at org.codehaus.stax2.ri.evt.Stax2FilteredEventReader.hasNext(Stax2FilteredEventReader.java:58) at org.keycloak.saml.processing.core.parsers.saml.SAMLAssertionParser.parse(SAMLAssertionParser.java:84) at org.keycloak.saml.processing.core.parsers.saml.SAMLResponseParser.parse(SAMLResponseParser.java:73) at org.keycloak.saml.processing.core.parsers.saml.SAMLParser.parse(SAMLParser.java:81) at org.keycloak.saml.common.parsers.AbstractParser.parse(AbstractParser.java:90) at org.keycloak.broker.saml.SAMLDataMarshaller.deserialize(SAMLDataMarshaller.java:85) at org.keycloak.authentication.authenticators.broker.util.SerializedBrokeredIdentityContext.deserialize(SerializedBrokeredIdentityContext.java:277) Best Regards Michael Mok