From f20dadb649891984437fa94d4b47d6c3f4a3acde Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
Date: Wed, 3 Feb 2021 16:13:09 +0000
Subject: Fix formatting for "bad session" error during sso registration flow
 (#9296)

---
 changelog.d/9296.bugfix |  1 +
 synapse/handlers/sso.py | 19 ++++++++++++++++---
 2 files changed, 17 insertions(+), 3 deletions(-)
 create mode 100644 changelog.d/9296.bugfix

diff --git a/changelog.d/9296.bugfix b/changelog.d/9296.bugfix
new file mode 100644
index 0000000000..d723f8c5bd
--- /dev/null
+++ b/changelog.d/9296.bugfix
@@ -0,0 +1 @@
+Fix bug in Synapse 1.27.0rc1 which meant the "session expired" error page during SSO registration was badly formatted.
diff --git a/synapse/handlers/sso.py b/synapse/handlers/sso.py
index b450668f1c..96ccd991ed 100644
--- a/synapse/handlers/sso.py
+++ b/synapse/handlers/sso.py
@@ -742,7 +742,11 @@ class SsoHandler:
             use_display_name: whether the user wants to use the suggested display name
             emails_to_use: emails that the user would like to use
         """
-        session = self.get_mapping_session(session_id)
+        try:
+            session = self.get_mapping_session(session_id)
+        except SynapseError as e:
+            self.render_error(request, "bad_session", e.msg, code=e.code)
+            return
 
         # update the session with the user's choices
         session.chosen_localpart = localpart
@@ -793,7 +797,12 @@ class SsoHandler:
             session_id,
             terms_version,
         )
-        session = self.get_mapping_session(session_id)
+        try:
+            session = self.get_mapping_session(session_id)
+        except SynapseError as e:
+            self.render_error(request, "bad_session", e.msg, code=e.code)
+            return
+
         session.terms_accepted_version = terms_version
 
         # we're done; now we can register the user
@@ -808,7 +817,11 @@ class SsoHandler:
             request: HTTP request
             session_id: ID of the username mapping session, extracted from a cookie
         """
-        session = self.get_mapping_session(session_id)
+        try:
+            session = self.get_mapping_session(session_id)
+        except SynapseError as e:
+            self.render_error(request, "bad_session", e.msg, code=e.code)
+            return
 
         logger.info(
             "[session %s] Registering localpart %s",
-- 
cgit 1.4.1