HAproxy bug: receipts api being handled by initial-sync worker

[watermelon0339]

Describe the bug
At times, requests to /_matrix/client/v3/rooms/{room_id}/receipt/m.read/{xxx} end up being handled by the initial-synchrotron worker.

Screenshots
Here’s the haproxy log output:

10.42.7.127:58106 [29/Jul/2025:00:42:10.600] synapse-http-in synapse-initial-synchrotron/initial-sync13 0/0/18259/0/46/18305 500 488 - - ---- 1031/1027/543/49/0 93/0 {matrix.my.domain||Element X/25.07.1 (OPPO PCDM10; Android 11; PCDM10_11_F.22; Sdk c5f2460e0)} "POST /_matrix/client/v3/rooms/!vaZLnlZZLicjbBJZZb:my.domain/receipt/m.read/$gK0lCxB9qUN666ZhW3qzNJe1x8l_GDkbPzU6hfa-mzc HTTP/1.1"

ESS and Device

• ESS: ess-helm 25.7.0
• Device: Element X 25.07.1

[benbz]

Thanks for raising this. The fix will be in the next release