I'm running 6.8.3 with fairly vanilla setup. I went to see if there were any updates and got a popup with nginx error 502. Thought that was odd so I tried to open a terminal window and got the same error. Tried to view the log using the web viewer, same error.

I SSH'ed into the server and restarted the nginx process which seemed to fix the inability to get the web-based terminal but the other two options I tried give me a 502.

 

I see this in /var/log/nginx/error.log:

2020/03/30 09:43:01 [error] 6991#6991: *17 connect() to unix:/var/run/emhttpd.socket failed (11: Resource temporarily un
available) while connecting to upstream, client: 192.168.254.100, server: , request: "GET /logging.htm?cmd=/plugins/dyna
mix.plugin.manager/scripts/plugin&arg1=checkos&csrf_token=82B2D868106A28B7 HTTP/1.1", upstream: "http://unix:/var/run/em
httpd.socket:/logging.htm?cmd=/plugins/dynamix.plugin.manager/scripts/plugin&arg1=checkos&csrf_token=82B2D868106A28B7",
host: "arthur.lan", referrer: "http://arthur.lan/Tools/Update"

2020/03/30 10:03:13 [error] 6991#6991: *472 connect() to unix:/var/run/emhttpd.socket failed (11: Resource temporarily u
navailable) while connecting to upstream, client: 192.168.254.100, server: , request: "GET /logging.htm?cmd=/plugins/dyn
amix.plugin.manager/scripts/plugin&arg1=checkos&csrf_token=82B2D868106A28B7 HTTP/1.1", upstream: "http://unix:/var/run/e
mhttpd.socket:/logging.htm?cmd=/plugins/dynamix.plugin.manager/scripts/plugin&arg1=checkos&csrf_token=82B2D868106A28B7",
host: "arthur.lan", referrer: "http://arthur.lan/Tools/Update"

2020/03/30 10:13:05 [error] 6991#6991: *774 connect() to unix:/var/run/emhttpd.socket failed (11: Resource temporarily u
navailable) while connecting to upstream, client: 192.168.254.100, server: , request: "POST /logging.htm HTTP/1.1", upst
ream: "http://unix:/var/run/emhttpd.socket:/logging.htm", host: "arthur.lan", referrer: "http://arthur.lan/Dashboard"

 

Any idea how to fix this?

Seems like it's something to do with emhttpd crashing:

 

See this in dmesg when I try to restart emhttpd:

[1728640.363470] emhttpd[9824]: segfault at 478 ip 0000000000412801 sp 00007fff235f4570 error 4 in emhttpd[403000+1b000]
[1728640.363478] Code: 8b 45 f0 48 89 c7 e8 5e ba ff ff 48 89 45 e8 48 8d 55 d0 48 8b 45 f0 48 89 d6 48 89 c7 e8 74 fa f
f ff 48 8b 55 d0 48 8b 45 e8 <48> 8b 80 78 04 00 00 48 29 c2 8b 45 cc 89 c6 bf ff 1c 42 00 b8 00
[1733417.480102] emhttpd[13602]: segfault at 478 ip 0000000000412801 sp 00007ffc6b087020 error 4 in emhttpd[403000+1b000
]
[1733417.480108] Code: 8b 45 f0 48 89 c7 e8 5e ba ff ff 48 89 45 e8 48 8d 55 d0 48 8b 45 f0 48 89 d6 48 89 c7 e8 74 fa f
f ff 48 8b 55 d0 48 8b 45 e8 <48> 8b 80 78 04 00 00 48 29 c2 8b 45 cc 89 c6 bf ff 1c 42 00 b8 00
[1733445.486722] emhttpd[13642]: segfault at 478 ip 0000000000412801 sp 00007fff5cbb20b0 error 4 in emhttpd[403000+1b000
]
[1733445.486728] Code: 8b 45 f0 48 89 c7 e8 5e ba ff ff 48 89 45 e8 48 8d 55 d0 48 8b 45 f0 48 89 d6 48 89 c7 e8 74 fa f
f ff 48 8b 55 d0 48 8b 45 e8 <48> 8b 80 78 04 00 00 48 29 c2 8b 45 cc 89 c6 bf ff 1c 42 00 b8 00

OK, so reboot seemed to fix the 502 issue but as soon as I started my array, the parity check operation kicked in. Not sure why as I didn't execute it manually and the box is configured to do it once a quarter (first Sunday of Jan, Apr, July, Oct). Is there a log file somewhere which would tell me why it decided to do the check?