SimpleSAML\Error\Error: UNHANDLEDEXCEPTION

Backtrace:
1 www/_include.php:17 (SimpleSAML_exception_handler)
0 [builtin] (N/A)
Caused by: Exception: Unable to find the SAML 2 binding used for this request.
Backtrace:
2 vendor/simplesamlphp/saml2/src/SAML2/Binding.php:107 (SAML2\Binding::getCurrentBinding)
1 modules/saml/lib/IdP/SAML2.php:356 (SimpleSAML\Module\saml\IdP\SAML2::receiveAuthnRequest)
0 www/saml2/idp/SSOService.php:26 (N/A)