Rendering some UI resources always fails with a 504 Bad Gateway

Issue

When accessing some UI sites, appears a 504 Bad Gateway as shown in the following screenshot:

Environment

Resolution

If you face a 504 Bad Gateway error only in some specific sites of the UI, (regardless if it’s constantly or intermittently) probably means that you are reaching a timeout threshold configured in some intermediate actor like Apache server, a Load Balancer like AWS ELB… If you collect a HAR file when the issue occurs, and search for the 504 you will probably see something like pasted below. Depending on your infra, you may not see something relevant at the server tag, but you will probably see a round number in the tag time like 60, 120, 180… (Please, take into consideration the measurement is in milliseconds, that’s why in the example below you see 60236 instead of 60).

If that’s the case, you have to contact your infrastructure administrator to remove the timeout threshold that is triggering the 504 Bad Gateway.

"response": {
 "status": 504,
 [...]
{
  "name": "server",
  "value": "awselb/2.0"
}
[...]
"time": 60236.0179999996,▼