GitHub Actions GITHUB_TOKEN Read-Only by Default - Write Calls 403

A write API call fails with 403 because the repository or organization default for GITHUB_TOKEN is read-only. The default scope is set in repo/org Actions settings and overridden per workflow with permissions:.

What this error means

A step that pushes, comments, or creates a release fails with "Resource not accessible by integration" even though the workflow looks correct - the default token permission is read-only.

Actions log

RequestError [HttpError]: Resource not accessible by integration (status 403)
# repo Settings > Actions > Workflow permissions = "Read repository contents"

Common causes

Repo/org default set to read-only

GitHub’s recommended default makes GITHUB_TOKEN read-only. Any write (contents, issues, packages) then 403s unless the workflow elevates it.

No permissions: block in the workflow

Without an explicit permissions: block, the job inherits the restrictive default, so write-needing steps are denied.

How to fix it

Grant the needed scope in the workflow

Add a least-privilege permissions: block at the workflow or job level for exactly what you write.

.github/workflows/ci.yml

permissions:
  contents: write     # only what this workflow needs
jobs:
  release:
    runs-on: ubuntu-latest
    steps: [{ run: ./publish.sh }]

Or adjust the repo/org default

In Settings > Actions > General, the "Workflow permissions" setting controls the default token scope.
Prefer keeping the default read-only and elevating per workflow with permissions:.
Set permissions at the job level when only one job needs write access.

How to prevent it

Keep the default token read-only and grant write per workflow.
Declare a least-privilege permissions: block in every write workflow.
Scope permissions to the job that needs them, not the whole workflow.