Issue
The following SAML errors appear in the Liferay logs:
ERROR [http-nio-8080-exec-5][BaseSamlStrutsAction:53] org.opensaml.messaging.decoder.MessageDecodingException: This message decoder only supports the HTTP POST method
com.liferay.saml.runtime.SamlException: org.opensaml.messaging.decoder.MessageDecodingException: This message decoder only supports the HTTP POST methodEnvironment
- Liferay DXP 7.4
Resolution
When using Liferay as the Service Provider (SP), this error indicates a mismatch in the HTTP method used for SAML communication between the SP and the Identity Provider (IdP). Liferay expects the SAML message through an HTTP POST binding, but receiving an alternative method (such as GET or REDIRECT) causes this error string. Follow these steps:
- Verify IdP Configuration: Ensure the IdP is configured to send SAML messages using the HTTP POST binding.
- Check Network Restrictions: Confirm that no network restrictions, such as firewalls or proxy settings between the SP and the IdP, alter or block communication methods.
- Confirm Artifact Resolution Support: The SAML 2.0 plugin in Liferay DXP does not support Artifact resolution. If the IdP requires it, this error occurs. Adjust the IdP configuration to use POST binding.