Log error when running the image to enroll the agent:

[2020-09-24T07:06:01.287Z] elastic-agent_1 | 2020-09-24T07:03:38.989Z ERROR operation/operation_retryable.go:85 operation operation-verify failed
[2020-09-24T07:06:01.287Z] elastic-agent_1 | 2020-09-24T07:03:38.989Z DEBUG application/periodic.go:40 Failed to read configuration, error: could not emit configuration: operator: failed to execute step sc-run, error: operation 'operation-verify' failed to verify metricbeat.8.0.0-SNAPSHOT: 3 errors occurred:
[2020-09-24T07:06:01.287Z] elastic-agent_1 | * fetching asc file from '/usr/share/elastic-agent/data/elastic-agent-d816b6/downloads/metricbeat-8.0.0-SNAPSHOT-linux-x86_64.tar.gz.asc': open /usr/share/elastic-agent/data/elastic-agent-d816b6/downloads/metricbeat-8.0.0-SNAPSHOT-linux-x86_64.tar.gz.asc: no such file or directory
[2020-09-24T07:06:01.287Z] elastic-agent_1 | * check detached signature: openpgp: invalid signature: hash tag doesn't match
[2020-09-24T07:06:01.287Z] elastic-agent_1 | * fetching asc file from https://artifacts.elastic.co/downloads/beats/metricbeat/metricbeat-8.0.0-SNAPSHOT-linux-x86_64.tar.gz.asc: call to 'https://artifacts.elastic.co/downloads/beats/metricbeat/metricbeat-8.0.0-SNAPSHOT-linux-x86_64.tar.gz.asc' returned unsuccessful status code: 404: /go/src/github.com/elastic/beats/x-pack/elastic-agent/pkg/artifact/download/http/verifier.go[205]: unknown error
[2020-09-24T07:06:01.287Z] elastic-agent_1 |
[2020-09-24T07:06:01.287Z] elastic-agent_1 | : operation 'operation-verify' failed to verify metricbeat.8.0.0-SNAPSHOT: 3 errors occurred:
[2020-09-24T07:06:01.287Z] elastic-agent_1 | * fetching asc file from '/usr/share/elastic-agent/data/elastic-agent-d816b6/downloads/metricbeat-8.0.0-SNAPSHOT-linux-x86_64.tar.gz.asc': open /usr/share/elastic-agent/data/elastic-agent-d816b6/downloads/metricbeat-8.0.0-SNAPSHOT-linux-x86_64.tar.gz.asc: no such file or directory
[2020-09-24T07:06:01.287Z] elastic-agent_1 | * check detached signature: openpgp: invalid signature: hash tag doesn't match
[2020-09-24T07:06:01.287Z] elastic-agent_1 | * fetching asc file from https://artifacts.elastic.co/downloads/beats/metricbeat/metricbeat-8.0.0-SNAPSHOT-linux-x86_64.tar.gz.asc: call to 'https://artifacts.elastic.co/downloads/beats/metricbeat/metricbeat-8.0.0-SNAPSHOT-linux-x86_64.tar.gz.asc' returned unsuccessful status code: 404: /go/src/github.com/elastic/beats/x-pack/elastic-agent/pkg/artifact/download/http/verifier.go[205]: unknown error

It seems that the .ASC is not present in none of the expected locations: filesystem or artifactory. So no process is able to start

Originally posted by @mdelapenya in #21120 (comment)