If sudo apt update fails with 567 Unknown Status or "repository is not signed" errors against a third-party mirror such as Tencent's, the practical fix is to reinstall the graphical Software & Updates tool with sudo apt install software-properties-gtk — Ubuntu 24.04 removed it from the default desktop install, which is why the mirror picker you remember seems to have vanished. Once it is back, you can switch to a working mirror in a couple of clicks instead of hand-editing repository files.
Why the mirror picker disappeared
For years, the Software & Updates application (software-properties-gtk) was included out of the box on Ubuntu desktop editions. In the 24.04 release it is no longer installed by default, so users upgrading from older versions often assume the feature was removed entirely. It was not — the package still exists in the archive, it just needs to be installed explicitly. On a server, or if the machine cannot reach any Ubuntu mirror at all, you will need to edit the sources file directly instead (more on that below).
Diagnosing the actual error
The HTTP status 567 is not a standard web error; it indicates the mirror returned something apt could not parse or trust. When apt cannot validate the InRelease file — because the mirror is stale, misconfigured, or serving an unexpected response — it reports the suites as "not signed" and disables them for your safety. This is apt's apt-secure mechanism doing its job, not a problem with your keyring.
Check two things before touching anything:
- Which suite is being requested. The source list should reference your release codename, for example
noblefor 24.04. If you see a future or development codename such asresoluteon a 24.04 machine, the sources file was copied from the wrong template or edited incorrectly — that alone will produce fetch errors on any mirror. - Whether the mirror itself is healthy. Open the failing URL in a browser (e.g.,
https://your-mirror/ubuntu/dists/noble/InRelease). If it errors there too, the mirror is the problem; if it downloads fine, suspect a local proxy or network issue.
Fixing it with the graphical tool
Install the legacy settings panel and launch it:
sudo apt update
sudo apt install software-properties-gtk
software-properties-gtk
In the Ubuntu Software tab, open the Download from dropdown, choose Other…, then Select Best Server to have Ubuntu test mirrors and pick the fastest responding one. Applying the change rewrites your sources configuration, after which sudo apt update should succeed.
Fixing it by hand on servers or broken systems
Ubuntu 24.04 uses the deb822 format rather than the old one-line sources.list entries. The active file is /etc/apt/sources.list.d/ubuntu.sources. Open it with an editor and replace the mirror hostname with a reliable one such as archive.ubuntu.com or your regional ?-archive.ubuntu.com variant:
sudo nano /etc/apt/sources.list.d/ubuntu.sources
Look for the URIs: line and change only the hostname, keeping the suites (noble, noble-updates, noble-backports) intact. Then refresh:
sudo apt update
Do not work around the signing errors with --allow-unauthenticated or by marking the repository as trusted. The error means the data could not be verified; switching to a healthy mirror preserves the signature checks.
Preventing a repeat
- Prefer official mirrors or your cloud provider's local mirror only after confirming it is actively synced.
- When copying source configuration from tutorials or other machines, verify the codename matches your release (
lsb_release -csprints it). - Keep
software-properties-gtkinstalled on desktop systems so the mirror picker stays available when you need it. - If an apt command keeps failing, run it again after fixing sources — stale partial downloads from the broken mirror occasionally linger and a second
apt updateclears them.
Frequently Asked Questions
Why does apt say the repository "is not signed" when the mirror is legitimate?
Apt verifies the InRelease file against Ubuntu's signing keys. If the mirror serves an empty, corrupted, or out-of-date file — common with poorly synced third-party mirrors — verification fails and apt reports the suite as unsigned, even though the archive itself is fine.
Is HTTP status 567 a real web error?
No. Standard HTTP codes only run to 599, and 567 is not in common use. Apt surfaces non-standard or unexpected responses from the mirror this way, which is why the accompanying IP address points at the mirror server rather than Ubuntu's infrastructure.
Can I keep using the Tencent or another regional mirror?
Yes, if it is currently healthy and correctly serving your release suite. The errors you saw were specific to that mirror at that moment, or to a wrong codename in the URL. Test the mirror's InRelease URL directly before committing to it.
Where do I edit sources on Ubuntu 24.04?
Desktop systems use /etc/apt/sources.list.d/ubuntu.sources in the deb822 format. Older one-line-style entries in /etc/apt/sources.list may also exist from third-party repositories; the Ubuntu entry lives in the .sources file.
What if sudo apt install software-properties-gtk also fails?
If every mirror is unreachable, temporarily point ubuntu.sources at archive.ubuntu.com by hand, run sudo apt update, then install the package. On a headless server you can simply keep editing the sources file manually and skip the GUI tool entirely.
Does downgrading repository security ever help here?
Never disable signature checks to force an update. The signing errors are the symptom, not the cause; a working mirror with valid signatures resolves the problem without weakening the system.