[CRITICAL/BUG] Cloudflare 520 Error on /user/m/client_health breaking client-side workflows & Set States across multiple apps

Bugs
1

Hi everyone and Bubble team,

We are experiencing a major issue affecting multiple independent applications simultaneously with no recent deploys. Client-side workflows and Set state actions are completely freezing because the platform’s internal telemetry heartbeat is failing.

Issue Details

  • Endpoint: POST /user/m/client_health

  • Status Code: HTTP 520 (Web Server Returned an Unknown Error)

  • Behavior: The Cloudflare proxy is returning an unknown origin error from Bubble’s backend servers. Because run.js does not gracefully handle this 520 response inside LocationService.response_to_error / rejectWith, it throws an unhandled exception that locks the JavaScript main thread.

  • Impact: Any client-side action (e.g., custom states, conditionals, visual updates) stops functioning as soon as this pulse request fails.

    pre_run_jquery.js:2 POST https://[domain]/user/m/client_health 520
    send @ pre_run_jquery.js:2
    ajax @ pre_run_jquery.js:2
    request @ run.js:315
    send_client_health @ run.js:321
    pulse @ run.js:321

    run.js:314 unexpected server response
    at LocationService.response_to_error (run.js:315:137568)
    at Object. (run.js:315:136882)
    at c (pre_run_jquery.js:2:28447)
    at Object.fireWith [as rejectWith] (pre_run_jquery.js:2:29192)
    at l (pre_run_jquery.js:2:80201)
    at XMLHttpRequest. (pre_run_jquery.js:2:82630)

    {
    “type”: " Error 520 · Cloudflare Support docs ",
    “title”: “Error 520: Web server is returning an unknown error”,
    “status”: 520,
    “detail”: “The origin web server sent a response that Cloudflare could not parse. This may indicate the origin returned an empty response, malformed HTTP headers, or an otherwise invalid response.”,
    “error_code”: 520,
    “error_name”: “unknown_origin_error”,
    “error_category”: “origin”,
    “ray_id”: “a3149047fe80b1f5”,
    “timestamp”: “2026-08-26T17:30:23Z”
    }

    Is anyone else experiencing this right now? A bug report has been submitted, but raising it here for immediate visibility from the engineering team.

    If you’re experiencing unexpected behavior and need immediate assistance, please file a bug report here: Contact | Bubble

@josh @fede.bubble

2

Same issue here, I dont fully understand the user impact but I can confirm I see the same error in the console.

3

The state setters aren’t working as they should; there are reports of users editing items and changing everything—for my exam report app, that’s fatal.

4

Same here a number of webhooks I have are failing

5

checking with the team

6

btw, are you all still actively being affected by this?

7

The cited error seems to have disappeared from the console, but “set state” errors still persist under specific conditions.

8

Yep I keep getting occasional Cloudflare issues when loading the site but keeping an eye on the webhooks

9

if you guys don’t mind, send me the app IDs impacted by this and some screenshots to my DMs. I’ll pass them on to engineering to speed up their investigation on what might be going on