GitHub Actions "Provided artifact name input during validation is empty"

The artifact action received an empty name. The name was built from an expression or variable that resolved to nothing - an unset matrix value, a missing output, or a typo in the context reference.

What this error means

An upload-artifact or download-artifact step fails validation with "Provided artifact name input during validation is empty", because the computed name string was blank.

Error: Provided artifact name input during validation is empty

Common causes

Name expression resolved to empty

A name like build-${{ steps.x.outputs.tag }} is empty when that output was never set, leaving the whole name (or its dynamic part) blank.

Unset matrix or env value in the name

Referencing matrix.<key> or env.VAR that is not present in this combination yields an empty segment, and an all-empty name fails validation.

How to fix it

Ensure the name resolves to a value

Provide a static fallback or confirm the dynamic part is always populated.

- uses: actions/upload-artifact@v4
  with:
    name: build-${{ matrix.os || 'default' }}
    path: dist/

Verify the source of the name

1. Echo the name expression in a prior step to confirm it is non-empty.
2. Make sure the producing step actually set the output you interpolate.
3. Default any optional matrix/env segment so the name is never blank.

How to prevent it

• Always include a non-empty static segment in artifact names.
• Confirm interpolated outputs/matrix values are set before use.
• Echo computed names when debugging artifact steps.

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