API `maproulette.org/api/v2/challenge/50887/rebuild` fails with `Bad Gateway Response`

I am calling updates to rebuild my challenges and for some (or sometimes) I get Bad Gateway Response

This is an example:
https://maproulette.org/api/v2/challenge/50887/rebuild?removeUnmatched=true&skipSnapshot=false

I am using removeUnmatched=true to cleanup old data first.

 Failed to trigger rebuild for challenge: Bad Gateway Response (6.33 KB) {
  ok: false,
  url: "https://maproulette.org/api/v2/challenge/50887/rebuild?removeUnmatched=true&skipSnapshot=false",
  status: 502,
  statusText: "Bad Gateway",
  headers: Headers {
    "date": "Tue, 18 Feb 2025 10:22:20 GMT",
    "content-type": "text/html; charset=UTF-8",
    "content-length": "6330",
    "connection": "keep-alive",
    "report-to": "{\"endpoints\":[{\"url\":\"https:\\/\\/a.nel.cloudflare.com\\/report\\/v4?s=xxx\"}],\"group\":\"cf-nel\",\"max_age\":604800}",
    "x-frame-options": "SAMEORIGIN",
    "referrer-policy": "same-origin",
    "cache-control": "private, max-age=0, no-store, no-cache, must-revalidate, post-check=0, pre-check=0",
    "expires": "Thu, 01 Jan 1970 00:00:01 GMT",
    "server-timing": "cfL4;desc=\"?proto=TCP&rtt=98605&min_rtt=98558&rtt_var=36993&sent=5&recv=6&lost=0&retrans=0&sent_bytes=3197&recv_bytes=882&delivery_rate=43832&cwnd=239&unsent_bytes=0&cid=29add4ebb9c06544&ts=75564&x=0\"",
    "nel": "{\"success_fraction\":0,\"report_to\":\"cf-nel\",\"max_age\":604800}",
    "server": "cloudflare",
    "cf-ray": "913d49cd9fd50f78-EWR",
    "alt-svc": "h3=\":443\"; ma=86400",
  },
  redirected: false,
  bodyUsed: false,
  Blob (6.33 KB)
}

I wonder if this is an error because the API tries to be synchronous but should be asynchronous?
What I expect to happen is, that I send the API call and get an "200 'request received'" response and then the server does the update asynchronously.

That is how I see it happen on the client when I use the rebuild-button, which loads a new web page and shows the progress bar.

Related questions

• Should I also add skipSnapshot=true? Do I want to add this? Does it make thinks faster?

Note to self:

• It looks like I can use the API to see if the rebuild was triggered (and is not finished, yet) by looking at challenge.status===1. Source1, Source2

Start by tracing the API rebuild endpoint and compare it with the client flow in src/components/AdminPane/Manage/ViewChallengeTasks/TaskBuildProgress.jsx and src/services/Challenge/ChallengeStatus/ChallengeStatus.js. Reproduce the 502 using the provided challenge URL and establish the expected response and status transitions for asynchronous rebuilds.