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GitHub Actions "Matrix vector has no values to expand"

By Kaveh Alemi·Latchkey

A matrix dimension resolved to an empty list, so there is nothing to expand and the job never runs.

What this error means

The matrix job is skipped or rejected because one of its vectors is empty, often after a fromJSON that produced [].

github-actions

The workflow is not valid. .github/workflows/ci.yml (Line: 10): Matrix vector 'version' does not contain any values

Common causes

A dynamic matrix produced an empty array

A matrix built from fromJSON of a job output can be [] when the upstream step emitted nothing.

An empty literal list

Declaring version: [] expands to zero combinations.

How to fix it

Guarantee at least one matrix value

Verify the upstream step emits a non-empty JSON array.
Fall back to a default value when the dynamic list is empty.

.github/workflows/ci.yml

strategy:
  matrix:
    version: ${{ fromJSON(needs.setup.outputs.versions) }}

How to prevent it

Log the JSON before feeding it into a matrix.
Add a guard job that fails clearly when the list is empty.

Frequently asked questions

What causes ""Matrix ... has no values""?

A matrix built from fromJSON of a job output can be [] when the upstream step emitted nothing.

How do I fix "Matrix ... has no values"?

Guarantee at least one matrix value

Related guides

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References

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