Too many connection_edge_process_relay_cell warnings

Hosting multiple hidden services on a Debian server running Tor 0.2.6.10 (no special setup or config options). I see thousands of such lines in the log files:

Jul 31 07:55:39.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 07:57:59.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:00:36.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:02:49.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:05:12.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:07:30.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:09:49.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:12:09.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:14:30.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:16:50.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:19:11.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:21:45.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:24:14.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:26:27.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:29:01.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:31:18.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:33:38.000 [warn] connection_edge_process_relay_cell (at origin) failed.
Jul 31 08:35:58.000 [warn] connection_edge_process_relay_cell (at origin) failed.

All hidden services are working and accessible, didn't reload/restart Tor. What is concerning is that there are so so many of these messages in a very short time. #9635 (moved) mentioned this as well, but along with other error messages which were indicating a wrong nTor key. Here we only have a single line, heavily repeated at short time intervals.