E: Failed to fetch ... 404 Not Found — Fix apt on Ubuntu/Debian

Q: Why do I get 404 in a Docker build?

Docker cached an old RUN apt-get update layer, so the install step uses outdated package lists. Combine update and install in a single RUN line, or rebuild with --no-cache .

Quick fix

Your package lists are probably out of date. Refresh them and run the same command again.

sudo apt update
sudo apt install packagename      # or: sudo apt upgrade

The full output usually looks like this:

Err:1 http://archive.ubuntu.com/ubuntu noble-updates/main amd64 libssl3t64 amd64 3.0.13-0ubuntu3.4
  404  Not Found [IP: 185.125.190.81 80]
E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/o/openssl/libssl3t64_3.0.13-0ubuntu3.4_amd64.deb  404  Not Found [IP: 185.125.190.81 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

What the error means

apt downloads packages based on its local index in /var/lib/apt/lists/, which it refreshes when you run apt update. The index says "version X of this package is at this path". A 404 means the server answered, but that file is not there any more.

First look at which URL failed, because it tells you which page you need:

Failing URL contains	Meaning	Fix
`/pool/.../something.deb`	One package file is gone; the repository is fine	This page, causes 1 to 4
`/dists/codename/InRelease` or `Release`	The whole release or repository is missing at that URL	Repository does not have a Release file
`ppa.launchpadcontent.net`	A PPA package or the PPA itself is gone	Cause 4

Cause 1: stale package lists

This is the cause most of the time. Ubuntu and Debian replace package versions in -updates and -security regularly, and old versions are removed from the pool after a while. If your last apt update was days or weeks ago, apt asks for a version that no longer exists. Refreshing the index makes apt request the current version:

sudo apt update
sudo apt upgrade

If apt update itself prints errors, fix those first; otherwise the index stays stale. A GPG warning there points to NO_PUBKEY; a missing Release file to the page linked above.

The hint about --fix-missing in the error is misleading: it makes apt skip the missing packages and continue, which can leave you with a partial upgrade. Only use it after apt update did not help and you understand which packages are skipped.

Cause 2: Docker and CI layer caching

In container builds, this error appears weeks after a Dockerfile worked fine. Docker cached the layer that ran apt-get update, so a later apt-get install layer uses the old index:

# problem: update is cached separately
RUN apt-get update
RUN apt-get install -y curl

Always update and install in the same RUN instruction, so they are cached (and invalidated) together:

RUN apt-get update \
 && apt-get install -y --no-install-recommends curl \
 && rm -rf /var/lib/apt/lists/*

For an existing image, rebuild with docker build --no-cache . or --pull to also refresh the base image. CI caches of /var/lib/apt/lists cause the same problem. More on images in Docker on Linux.

Cause 3: a broken or out-of-sync mirror

Country mirrors such as de.archive.ubuntu.com, or a university or hosting provider mirror, sync from the main archive on a schedule. During or after a failed sync, the index and the files can disagree. If apt update did not help and the failing host is a mirror, switch to the main archive:

# Ubuntu 24.04+ (deb822 format)
grep -n URIs /etc/apt/sources.list.d/ubuntu.sources
sudo sed -i 's|http://[a-z]*\.archive\.ubuntu\.com|http://archive.ubuntu.com|' /etc/apt/sources.list.d/ubuntu.sources
# Debian: deb.debian.org is a CDN that picks a good mirror automatically
grep -rn URIs /etc/apt/sources.list.d/ /etc/apt/sources.list 2>/dev/null
sudo apt update

On Debian, use http://deb.debian.org/debian and http://security.debian.org/debian-security. On older Ubuntu installs the URLs live in /etc/apt/sources.list. Our apt guide explains both source formats.

An HTTP proxy or a local cache such as apt-cacher-ng can also serve stale data. Clear its cache, or bypass it to test with sudo apt -o Acquire::http::Proxy=false update. A captive portal (hotel or public Wi-Fi login page) can produce 404s or hash mismatches too; open a browser and log in first.

Cause 4: a PPA or third-party repository changed

PPAs and vendor repositories delete old versions more aggressively than the main archive, and some disappear entirely. If the failing URL is a PPA or a vendor host, refresh first; if the 404 persists for the repository's index, the source no longer supports your release. List third-party sources:

ls /etc/apt/sources.list.d/

Disable the offending one by moving it away (or setting Enabled: no in a .sources file), then update:

sudo mv /etc/apt/sources.list.d/some-ppa.sources /root/
sudo apt update

Check the vendor's current install instructions: many projects moved their repository URL or signing key in recent years, and the old URL now returns 404.

Cause 5: an end-of-life release

When an Ubuntu release reaches end of life, its packages are removed from archive.ubuntu.com and security.ubuntu.com and moved to old-releases.ubuntu.com. Ubuntu 25.10 reached EOL in July 2026, so a 25.10 system now gets 404 errors for everything. The fix is to point apt at old-releases briefly and upgrade to a supported release; the steps are on the no Release file page and in the Ubuntu upgrade guide. Debian releases past LTS move to archive.debian.org in the same way.

Distro notes

Linux Mint: Mint's own packages come from packages.linuxmint.com, the rest from Ubuntu (or Debian for LMDE). Use the Software Sources tool to pick another mirror if one is broken; the sources are in /etc/apt/sources.list.d/official-package-repositories.list.
Kali and Debian testing/unstable: packages change daily, so an index older than a day or two can already give 404s. Always apt update right before installing.
Raspberry Pi OS: uses archive.raspberrypi.com plus Debian mirrors; same fixes apply.
Fedora (dnf): the equivalent is a Status code: 404 during download. Refresh metadata with sudo dnf clean metadata and sudo dnf upgrade --refresh; see Failed to download metadata.
Arch (pacman): failed retrieving file ... 404 means your sync database is outdated. Run sudo pacman -Syu (never -Sy plus a single package, which creates a partial upgrade).
openSUSE (zypper): run sudo zypper refresh, then retry.

How to prevent it

Run sudo apt update immediately before every install or upgrade; scripts should do the same.
In Dockerfiles, keep apt-get update and apt-get install in one RUN line.
Use the default archive or deb.debian.org unless you have a reason to pin a specific mirror.
Track your release's support dates and upgrade before end of life.

Frequently asked questions

Why does apt say 404 Not Found?

apt requested a file listed in its local package index, but the server no longer has it. Usually the index is old and the package has been replaced by a newer version, so sudo apt update fixes it.

Does apt-get install --fix-missing fix 404 errors?

Rarely. It only skips the packages that failed to download. Refresh the package lists with sudo apt update first; that is what actually fixes a stale index.

Why do I get 404 in a Docker build?

Docker cached an old RUN apt-get update layer, so the install step uses outdated package lists. Combine update and install in a single RUN line, or rebuild with --no-cache.

What if the 404 is for a Release or InRelease file?

Then the whole repository or release is gone from that URL, not just one package. That is covered on our no Release file page: typically an end-of-life release or a PPA without builds for your version.

Spotted a mistake or a command that no longer works? Send a correction — pages are re-checked when reports come in.

Fix "E: Failed to fetch ... 404 Not Found" in apt