Don't try to serialise a non-hashable obj

Author: anoadragon453

synapse/rest/media/v1/upload_resource.py

@@ -101,6 +101,8 @@ async def _async_render_POST(self, request: SynapseRequest) -> None:
             # the default 404, as that would just be confusing.
             raise SynapseError(400, "Bad content")
 
-        logger.info("Uploaded content with URI %r", content_uri)
+        logger.info(f"Uploaded content with URI {content_uri}")
 
-        respond_with_json(request, 200, {"content_uri": content_uri}, send_cors=True)
+        respond_with_json(
+            request, 200, {"content_uri": str(content_uri)}, send_cors=True
+        )