Hi Everyone, We’re running Open edX Ulmo on Tutor v21 (tutor, version 21.0.9) deployed on AWS EC2. The setup has no customizations apart from brand color and logo. The build was working fine previously, but now when I run: tutor images build mfe --no-cache the build fails while installing system…

I found something more details is MFE container is using Debian 11 Bullseye. Debian 11 Bullseye reached LTS end-of-life on August 31, 2026 — only a few days ago. Debian officially says Bullseye is no longer receiving further security updates after August 31, 2026. Debian -- News -- Debian 11 Long …

Your EOL diagnosis is right, though the specific failure is narrower than a stale index. bullseye-security’s Release file is still being served (dated Aug 31) and still advertises exactly the versions in your log (linux-libc-dev 5.10.262-1, libc-dev-bin 2.31-13+deb11u14, libperl5.32 5.32.1-4+deb11u5…

Hi I’ve submitted a pull request covering a potential fix for this issue, it could also be backported to Teak (where I’m also facing the same issue).

The new tutor-mfe release v22.1.0 , containing a fix for this, is out. Thanks, @WillEVTdigital for your contribution.

No problem! For older releases not covered by this fix you can use a high priority ENV_TEMPLATE_ROOTS e.g. Teak v20.1.0 customplugin/plugin.py hooks.Filters.ENV_TEMPLATE_ROOTS.add_item( str(importlib_resources.files("customplugin") / "template_overrides"), priority=hooks.priorities.HIGH, ) …

MFE Docker image build failing — apt 404 errors on Debian bullseye packages

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Abdul_Muqadim (Abdul Muqadim) September 17, 2026, 6:46pm 7

We have back ported this fix to ulmo, teak, sumac and redwood as well, for more info refer to Tutor-mfe: bullseye EOL fix backported to Redwood, Sumac, Teak and Ulmo

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MFE Docker image build failing — apt 404 errors on Debian bullseye packages

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