Fix #10252: cabal upload fails with curl chunked-encoding error by tusharad · Pull Request #12211 · haskell/cabal

tusharad · 2026-08-04T16:30:00Z

Description

Newer versions of curl misinterpret the literal \n character embedded within the --write-out "\n%{http_code}" argument during chunked-encoding transfers (such as POST and PUT requests used in cabal upload). This results in curl: (56) Illegal or missing hexadecimal sequence in chunked-encoding errors.

This PR:

Removes the newline character from the --write-out parameter for both posthttpfile and puthttpfile.
Adjusts parseResponse in curlTransport (and extracts it as parseCurlResponse) to extract the 3-digit HTTP status code directly from the end of the response string, avoiding the need to split the string by lines.
Adds test cases for parseCurlResponse in UnitTests.Distribution.Client.HttpUtils.

QA Notes

Calling cabal upload <package>.tar.gz on a system with a newer version of curl installed should succeed without throwing a curl: (56) chunked-encoding error, correctly parsing the upload status code.

Template Α: This PR modifies behaviour or interface

Patches conform to the coding conventions.
Any changes that could be relevant to users have been recorded in the changelog.
- Is the change significant? If so, remember to add significance: significant in the changelog file. (Note: Not checked as this is a bug fix, but you may check this if you feel it's a highly visible bug fix)
The documentation has been updated, if necessary.
Manual QA notes have been included.
Tests have been added.

ffaf1 · 2026-08-04T16:59:47Z

Hello and thanks for your contribution.

This PR is missing a template (here).

ulysses4ever · 2026-08-04T17:41:47Z

wow, if this really fixes it, it's a big one. Maybe we should even consider a lightning 3.18.1.1. release.. And it only touches the tool

Mikolaj · 2026-08-06T11:43:30Z

Yay! BTW, a changelog snippet would also be welcome.

tusharad · 2026-08-07T11:36:23Z

Hello,
below are screens showcasing cabal upload failing and my cabal modifications fixing the upload.

https://github.com/tusharad/sql2er/actions/runs/31173210576/job/92849383471
https://github.com/tusharad/sql2er/actions/runs/31173199134

@Mikolaj is this changelog enough? https://github.com/haskell/cabal/pull/12211/changes#diff-60db094ee10f0a5f3f9cd8a8a15959da265886a020fd4f55d6028f80846a5dbe

@ffaf1 @ulysses4ever can you review and approve this PR?

Mikolaj · 2026-08-07T11:49:40Z

@Mikolaj is this changelog enough? https://github.com/haskell/cabal/pull/12211/changes#diff-60db094ee10f0a5f3f9cd8a8a15959da265886a020fd4f55d6028f80846a5dbe

Looks good, thank you.

ulysses4ever · 2026-08-07T16:33:27Z

Will do. Hopefully on the weekend

ulysses4ever · 2026-08-07T23:28:33Z

cabal upload .tar.gz on a system with a newer version of curl installed should succeed

Is three any info on which curl do and don't work? Does this patch support both of these cases or only newer curl?

ffaf1

I left some comments. I am aware not all code is yours, some is just shuffled around, but if we are refactoring stuff (good!) it might be a good opportunity to clean some code.

ulysses4ever

We could have merged it in an instant if you had just kicked out the \n. Instead, you introduced a subtle refactoring that'a completely unrelated, and we'll spend much more time reviewing it. Please, don't introduce unrelated changes in one PR especially when you're fixing high-priority bugs like this one.

The best way to proceed would be to reset this patch to a state when it only removes the \n. And leave all rest for another PR. I'm not saying you must do it, it's just the easiest and most effective. But if you prefer keeping it as one PR, we can work with it.

tusharad · 2026-08-08T12:50:28Z

Hello @ulysses4ever and @ffaf1
Thank you for the detailed review, either I'll try to fix them or create a new PR for this. Meanwhile please a look at this.

https://github.com/tusharad/sql2er/actions/runs/31257218055 - Seems like curl 7.6 to 8.5 are breaking while passing on latest cabal.

my fixed is passing on all - https://github.com/tusharad/sql2er/actions/runs/31257224015

Btw on my mac, the issue is not appearing at all. Linux specific?

ffaf1 · 2026-08-10T08:29:07Z

[x] Tests have been added.

There are no tests in this PR.

…puthttpfile

…encoding upload failures

…abal into fix/cabal-upload-fail

…characters of the response body

… parsing

tusharad · 2026-08-10T13:44:16Z

[x] Tests have been added.

There are no tests in this PR.

My bad, the commit revert had it removed. Added them now. @ffaf1

tusharad · 2026-08-15T15:12:41Z

@ffaf1 I think it can be merged?

ffaf1 · 2026-08-15T15:57:09Z

Sure, I have put the merge me label, now mergify will take care of it in two days (the buffer period this project has for additional feedback).

mergify · 2026-08-17T17:01:27Z

zlonast · 2026-08-29T14:14:29Z

@mergify backport 3.18

mergify · 2026-08-29T14:14:35Z

backport 3.18

✅ Backports have been created

Details

#12297 Backport #12211: Fix #10252: cabal upload fails with curl chunked-encoding error has been created for branch 3.18

Backport #12211: Fix #10252: cabal upload fails with curl chunked-encoding error

haskell#12211) * fix: remove newline from curl --write-out option in posthttpfile and puthttpfile * test: add unit tests for HttpUtils and document fix for curl chunked-encoding upload failures * chore: update synopsis for cabal upload error fix in changelog * refactor: update HTTP status code extraction to parse the last three characters of the response body * docs: clarify status code extraction logic in HttpUtils curl response parsing (cherry picked from commit ca805f1)

tusharad changed the title ~~test: add unit tests for parseCurlResponse and refactor logic into an exported function~~ Fix #10252: cabal upload fails with curl chunked-encoding error Aug 4, 2026

ffaf1 reviewed Aug 8, 2026

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ulysses4ever reviewed Aug 8, 2026

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Comment thread cabal-install/src/Distribution/Client/HttpUtils.hs Outdated

Comment thread cabal-install/src/Distribution/Client/HttpUtils.hs Outdated

Comment thread cabal-install/src/Distribution/Client/HttpUtils.hs

Comment thread cabal-install/src/Distribution/Client/HttpUtils.hs Outdated

tusharad force-pushed the fix/cabal-upload-fail branch from 03a4df4 to 2e9536d Compare August 8, 2026 13:03

tusharad requested review from ffaf1 and ulysses4ever August 8, 2026 16:41

ulysses4ever approved these changes Aug 8, 2026

View reviewed changes

tusharad force-pushed the fix/cabal-upload-fail branch 2 times, most recently from 723e949 to e2d6813 Compare August 10, 2026 10:17

fix: remove newline from curl --write-out option in posthttpfile and …

24f4aa8

…puthttpfile

tusharad force-pushed the fix/cabal-upload-fail branch from 49ef270 to 24f4aa8 Compare August 10, 2026 10:23

tusharad and others added 6 commits August 10, 2026 15:54

Merge branch 'master' into fix/cabal-upload-fail

e8a5e59

test: add unit tests for HttpUtils and document fix for curl chunked-…

cb4a8b7

…encoding upload failures

Merge branch 'fix/cabal-upload-fail' of https://github.com/tusharad/c…

2d138f5

…abal into fix/cabal-upload-fail

chore: update synopsis for cabal upload error fix in changelog

a34aa0c

refactor: update HTTP status code extraction to parse the last three …

37eea88

…characters of the response body

docs: clarify status code extraction logic in HttpUtils curl response…

8f13d09

… parsing

ffaf1 approved these changes Aug 10, 2026

View reviewed changes

Merge branch 'master' into fix/cabal-upload-fail

4a8fd81

ffaf1 added the squash+merge me Tell Mergify Bot to squash-merge label Aug 15, 2026

mergify Bot added ready and waiting Mergify is waiting out the cooldown period merge delay passed Applied (usually by Mergify) when PR approved and received no updates for 2 days queued labels Aug 15, 2026

mergify Bot mentioned this pull request Aug 17, 2026

merge queue: checking master (a21f354) and #12211 together #12243

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mergify Bot merged commit ca805f1 into haskell:master Aug 17, 2026
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mergify Bot removed the queued label Aug 17, 2026

ulysses4ever added the attention: needs-backport 3.18 label Aug 19, 2026

ffaf1 mentioned this pull request Aug 28, 2026

Release checklist for 3.18.2.0 (minor release) #12295

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mergify Bot mentioned this pull request Aug 29, 2026

Backport #12211: Fix #10252: cabal upload fails with curl chunked-encoding error #12297

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mergify Bot added a commit that referenced this pull request Aug 29, 2026

Merge pull request #12297 from haskell/mergify/bp/3.18/pr-12211

4f8ce45

Backport #12211: Fix #10252: cabal upload fails with curl chunked-encoding error

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