Getting "not found" after authenticating when trying to initiate GitHub workflow via REST - github

Question

I am trying to trigger the workflow_dispatch action for a GitHub workflow via REST but I am getting a "not found" error.
My question is similar to this one but the difference is that I am still getting the "not found" error even though the header indicates I am authenticated (the rate limit has increased to 5,000).
Here's my script:
#!/bin/bash
# https://docs.github.com/en/rest/reference/actions#create-a-workflow-dispatch-event
OWNER='myGithubOrganization'
REPO='myRepo'
WORKFLOW_ID='main.yml'
POST_URL="https://api.github.com/repos/$OWNER/$REPO/actions/workflows/$WORKFLOW_ID/dispatches"
echo "Calling $POST_URL"
GITHUB_PERSONAL_ACCESS_TOKEN=$(echo "$PLATFORM_VARIABLES" | base64 --decode | jq '.GITHUB_PERSONAL_ACCESS_TOKEN' --raw-output)
# -i to include headers.
curl \
-i \
-X POST \
-H "Accept: application/vnd.github.v3+json" \
-H "Authorization: token $GITHUB_PERSONAL_ACCESS_TOKEN" \
$POST_URL \
-d '{"ref":"ref"}'
In the headers, I see the rate limit has increased to 5,000, so I know I am logged in.
The personal access token has the following permissions:
repo
workflow
admin:org_hook
The personal access token is for a machine user.
In the repo settings, under "Collaborators and teams", the machine user account has the "Read" role.
What more do I need to do to trigger the workflow?

Answer 1

The machine user needs to have write access, not read access.
This is true even if the workflow does something like run CI tests and does not write any code.