1 files changed, 2 insertions, 0 deletions
diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py
index ad865a667f..7226abd829 100644
--- a/synapse/config/saml2_config.py
+++ b/synapse/config/saml2_config.py
@@ -189,6 +189,8 @@ class SAML2Config(Config):
         import saml2
 
         public_baseurl = self.public_baseurl
+        if public_baseurl is None:
+            raise ConfigError("saml2_config requires a public_baseurl to be set")
 
         if self.saml2_grandfathered_mxid_source_attribute:
             optional_attributes.add(self.saml2_grandfathered_mxid_source_attribute)