What Docker Could Not Push
Docker cannot push the image because the tag does not exist locally, so you need to tag the image correctly before pushing.
Check the local tag before push
Print the exact image reference the push step is using.
List local image tags on the current daemon with docker image ls and confirm that exact tag exists.
If the image was built earlier in CI, verify the tag step ran on the same runner before the push.
Tag the local image before pushing
List local image tags and identify the source image you actually built or pulled.
Tag that image with the exact destination reference:docker tag <source-image> <registry>/<repo>:<tag>
Push the same fully qualified tag you just created.
Why the Local Tag Is Missing
The image exists locally, but under a different tag than the push step expects.
The docker tag step never ran or tagged the wrong destination reference.
The push step runs on a runner that does not have the image tagged locally.
Verify the Local Tag Exists and the Push Works
Run docker image inspect <registry>/<repo>:<tag> locally and confirm the tag exists before pushing, and run docker push <registry>/<repo>:<tag> and confirm the push succeeds.
Typical Output
Error pushing to registry: Tag does not exist: <tag>Avoid Version and Source Drift
To prevent this, use one canonical image reference variable for build, tag, and push steps in CI, and log the final image reference before push so tag drift is obvious in the job output.
How Docker decides which local tag to push
docker push can only push a local image tag that already exists on the current daemon.
If the local tag is missing, Docker has nothing to upload for that destination reference and the push stops immediately.