1 files changed, 5 insertions, 0 deletions
diff --git a/synapse/logging/context.py b/synapse/logging/context.py
index a8eafb1c7c..3254d6a8df 100644
--- a/synapse/logging/context.py
+++ b/synapse/logging/context.py
@@ -539,6 +539,11 @@ def set_current_context(context: LoggingContextOrSentinel) -> LoggingContextOrSe
     Returns:
         The context that was previously active
     """
+    # everything blows up if we allow current_context to be set to None, so sanity-check
+    # that now.
+    if context is None:
+        raise TypeError("'context' argument may not be None")
+
     current = current_context()
 
     if current is not context: