[Bug]: Self update send warning when using ghcr.io private key

[ivancarlosti]

Bug Report Checklist

• I checked existing issues and found no duplicates.
• I have reviewed Watchtower's documentation and confirmed compliance with documented configuration specifications.
• I have restarted Docker, re-pulled the latest image, and confirmed that the issue persists.

Bug Description

My Watchtower cames from Docker.io:

Looks like it tries to self update using ghcr.io because I have a private ghcr.io key and it sends a warning on every execution, followed by a sucess message after 5 minutes

It's not clear to me why it always fails when a private key is loaded ir it's a multiday coincidence

Steps to Reproduce

1. Wait for update schedule
2. Get warning

Expected Behavior

Update without warning

Watchtower Version

latest

Docker Version

Client: Docker Engine - Community
 Version:           29.1.5
 API version:       1.52
 Go version:        go1.25.6
 Git commit:        0e6fee6
 Built:             Fri Jan 16 12:49:41 2026
 OS/Arch:           linux/arm64
 Context:           default

Docker Info (optional)

Docker Compose Configuration

watchtower:
    container_name: containerupdate
    image: nickfedor/watchtower
    restart: unless-stopped
    environment:
      - TZ=America/Sao_Paulo
      - WATCHTOWER_CLEANUP=true
      - WATCHTOWER_SCHEDULE=0 0 6 * * *
      - WATCHTOWER_INCLUDE_RESTARTING=true
      - WATCHTOWER_INCLUDE_STOPPED=true
      - WATCHTOWER_REVIVE_STOPPED=true
      - WATCHTOWER_ROLLING_RESTART=false
      - WATCHTOWER_NOTIFICATION_URL=supressed
      - WATCHTOWER_NOTIFICATION_DELAY=2
      - WATCHTOWER_NOTIFICATION_TITLE_TAG=supressed
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /root/.docker/config.json:/config.json:ro
    deploy:
      resources:
        limits:
          memory: 768M

Docker CLI Command

Debug Logs

containerupdate | time="2026-07-06T06:00:00-03:00" level=info msg="Watchtower self-update pull failed - sleeping to prevent rapid restarts" delay=5m0s
containerupdate | time="2026-07-06T06:05:00-03:00" level=info msg="Update session completed" failed=0 notify=no scanned=0 updated=0

Additional Context

No response

[nicholas-fedor]

The latest release included some improvements that may have resolve this issue.
Please confirm if you're still seeing this problem. If it's still impacting you, then please provide debug logs so that I may attempt to identify the cause of the issue.