3.x Task Runs went missing from 3.0.0rc18 to 3.0.0rc19

TL;DR

Issue PrefectHQ/prefect#15153 (closed, 50 comments): ### Bug summary Up until 3.0.0rc18 task run completions were registered correctly with a local Prefect server, but after that with 3.0.0rc19 and 3.0.0rc20 the list of task runs remain empty even after all tasks were completed successfully.

Steps

1. Issue PrefectHQ/prefect#15153 (closed, 50 comments): ### Bug summary Up until 3.0.0rc18 task run completions were registered correctly with a local Prefect server, but after that with 3.0.0rc19 and 3.0.0rc20 the list of task runs remain empty even after all tasks were completed successfully. So, nothing will be listed on a dashboard URL like that: the service URL for that host and port I am still investigating the issue, but downgrading helped to solved it for me.
2. If task runs are missing from the Prefect 3.x UI, upgrade the server and client past 3.1.3, which fixed the likely cause, and check that the browser can establish the websocket connection to the server (newer versions warn when it cannot). The maintainer closed the original report once those fixes shipped; if it persists on current versions, open a new issue with a minimal repro.

When to use

You are seeing this: So, nothing will be listed on a dashboard URL like that: the service URL for that host and port I am still investigating the issue, but downgrading helped to solved it for me. Use this skill when you run into "3.x Task Runs went missing from 3.0.0rc18 to 3.0.0rc19".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

Versions mentioned in the source: past 3.1.3. If you are on something much newer or older, the details may have shifted.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.