Artifact download fails when the artifact name contains certain Non-ASCII (Japanese) characters

[mkht]

Why are you starting this discussion?

Bug

What GitHub Actions topic or product is this about?

Workflow Deployment

Discussion Details

I reported this issue to actions/download-artifact#465 , but I thought it would be more appropriate to report it to the discussion, so I am reposting it here.

What happened?

If the artifact name contains certain non-ASCII characters (Japanese), download-artifact fails.

It appears to fail with a 400 error when downloading from Azure Blob Storage. After 5 retries, the step exits with an error.

##[debug][Request] GetSignedArtifactURL https://results-receiver.actions.githubusercontent.com/twirp/github.actions.results.api.v1.ArtifactService/GetSignedArtifactURL
##[debug][Response] - 200
##[debug]Headers: {
##[debug]  "content-length": "643",
##[debug]  "content-type": "application/json",
##[debug]  "date": "Tue, 24 Feb 2026 14:49:06 GMT",
##[debug]  "x-github-backend": "Kubernetes",
##[debug]  "x-github-request-id": "9C19:33389F:11807C:133FB6:699DBA62"
##[debug]}
::add-mask::***
::add-mask::***
##[debug]Body: {
##[debug]  "signed_url": "https://productionresultssa12.blob.core.windows.net/actions-results/7ea21df8-7342-4034-9be6-d267ad4a3d8f/workflow-job-run-f0b32962-6d5d-5037-9abc-0165fe5c29f7/artifacts/753afa6619671708edf18d9596d37bc01e35be69045e73e185bc68681ef389c9.zip?rscd=attachment%3B+filename%3D%22probe-%E5%9C%9F-x.zip%22&rsct=application%2Fzip&se=2026-02-24T14%3A59%3A06Z&sig=***&ske=2026-02-24T16%3A48%3A58Z&skoid=ca7593d4-ee42-46cd-af88-8b886a2f84eb&sks=b&skt=2026-02-24T12%3A48%3A58Z&sktid=398a6654-997b-47e9-b12b-9515b896b4de&skv=2025-11-05&sp=r&spr=https&sr=b&st=2026-02-24T14%3A49%3A01Z&sv=2025-11-05"
##[debug]}
Redirecting to blob download url: https://productionresultssa12.blob.core.windows.net/actions-results/7ea21df8-7342-4034-9be6-d267ad4a3d8f/workflow-job-run-f0b32962-6d5d-5037-9abc-0165fe5c29f7/artifacts/753afa6619671708edf18d9596d37bc01e35be69045e73e185bc68681ef389c9.zip
Starting download of artifact to: /home/runner/work/actions-test-202602/actions-test-202602/downloaded
##[debug]Failed to download artifact after 1 retries due to Unexpected HTTP response from blob storage: 400 Value for one of the query parameters specified in the request URI is invalid.. Retrying in 5 seconds...
##[debug]Failed to download artifact after 2 retries due to Unexpected HTTP response from blob storage: 400 Value for one of the query parameters specified in the request URI is invalid.. Retrying in 5 seconds...
##[debug]Failed to download artifact after 3 retries due to Unexpected HTTP response from blob storage: 400 Value for one of the query parameters specified in the request URI is invalid.. Retrying in 5 seconds...
##[debug]Failed to download artifact after 4 retries due to Unexpected HTTP response from blob storage: 400 Value for one of the query parameters specified in the request URI is invalid.. Retrying in 5 seconds...
##[debug]Failed to download artifact after 5 retries due to Unexpected HTTP response from blob storage: 400 Value for one of the query parameters specified in the request URI is invalid.. Retrying in 5 seconds...
Error: Unable to download artifact(s): Unable to download and extract artifact: Artifact download failed after 5 retries.

The issue does not occur with all non-ASCII characters.
For example, “日” (U+65E5) works without issue, but “土” (U+571F) results in an error. Both are common Kanji characters widely used in Japanese.
I thought a specific code point might be involved, but the exact conditions are unclear.

To investigate this issue, I created a test repository.
I tried 20 different Kanji characters: 5 succeeded and 15 failed.
Please see the full workflow log:
https://github.com/mkht/actions-test-202602/actions/runs/22355207590

What did you expect to happen?

Success download artifacts

How can we reproduce it?

A minimal reproducible workflow:

name: Artifact-Test-2

on:
  workflow_dispatch:

jobs:
  non_ascii_artifact:
    name: Non-ASCII artifact
    runs-on: ubuntu-latest

    steps:
      - name: Create test file
        run: |
          mkdir -p source
          printf 'artifact-content-%s\n' "$(date -u +%Y%m%dT%H%M%SZ)" > source/test.txt

      - name: Upload artifact
        uses: actions/upload-artifact@v6
        with:
          name: 土 #U+571F
          path: source/test.txt
          if-no-files-found: error

      - name: Download artifact
        uses: actions/download-artifact@v7
        with:
          name: 土 #U+571F
          path: downloaded

Anything else we need to know?

This issue did not occur until 2026-02-23. It has been occurring since 2026-02-24.
No code changes were made.
Recent changes in GitHub or Azure backend systems may have affected this behavior.

What version of the action are you using?

v7.0.0

What are your runner environments?

linux

Are you on GitHub Enterprise Server? If so, what version?

No

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[mkht]

I hope GitHub investigates this issue.