While testing the externally-accessible goma backend, the goma client failed a DCHECK during a build:

F1112 09:39:48.871924 24549 compile_task.cc:2487] Check failed: !hash_key.empty() /home/mostyn/code/upstream/src/out/google-goma/obj/device/bluetooth/bluetooth/bluetooth_adapter_bluez.o

Grepping through the logs a bit, this might be the root cause:

W1112 09:39:47.420526 24561 http.cc:1962] Task:8405 AsyncFileTask connection closed before receiving all data at 429108
W1112 09:39:48.730278 24561 compile_task.cc:732] Task:8405 no-cached output file failed:/home/mostyn/code/upstream/src/out/google-goma/obj/device/bluetooth/bluetooth/bluetooth_adapter_bluez.o
E1112 09:39:48.866246 24549 compile_task.cc:4946] Task:8405 Failed to write file blob:obj/device/bluetooth/bluetooth/bluetooth_adapter_bluez.o (no-cached)
W1112 09:39:48.866283 24549 compile_task.cc:4365] Task:8405 will retry with STORE_ONLY
E1112 09:39:48.869313 24549 compile_task.cc:4946] Task:8405 Try:1: Failed to download 3 files in no-cachedresult
E1112 09:39:48.869367 24549 compile_task.cc:4946] Task:8405 http is unhealthy. no retry. health_status=running: had some http errors from backend servers
I1112 09:39:48.869457 24549 compile_task.cc:2084] Task:8405 finished failed in file response state=FILE_RESP abort=0 canceled=0