Unexpected character error pulling from remote docker repo

DockerFacetUtils - Could not parse error response Unexpected character ('<' (code 60))

No problem on the command line doing a docker login & pull.
But when I try to set up a remote docker proxy repo to remote.docker.repo in Nexus, I can’t seem to get it working. I am using Username Authentication, as the remote repo requires it.

command line

$ docker login remote.docker.repo
WARNING! Your password will be stored unencrypted in /root/.docker/config.json.
Configure a credential helper to remove this warning. See
Login Succeeded

$ docker pull remote.docker.repo/prod/another-namespace-here/payment:3.34
Trying to pull repository remote.docker.repo/prod/another-namespace-here/payment ... 
3.34: Pulling from remote.docker.repo/prod/another-namespace-here/payment
4040fe120662: Pull complete 
7ff62d377d7f: Pull complete 
d408fe38480f: Pull complete 
Digest: sha256:d14c388bb7fb5b1190d99f234ef0c1f7438c86a54ba462365c7da4cf54af2b28
Status: Downloaded newer image for remote.docker.repo/prod/another-namespace-here/payment:3.34

Seems like I may be running into NEXUS-18263 not sure. I do not have access to the remote repo to make any config changes and I’ve tried all kinds of permutations in the remote storage url field.

Here is the logging when I try to pull the image through the proxy using a command like: docker pull my.nexus.server/prod/another-namespace-here/payment:3.34

2022-10-19 20:13:26,645+0000 TRACE [qtp2044915405-391638]  service-jenkins org.sonatype.nexus.repository.docker.internal.DockerGroupHandler - Trying member: RepositoryImpl$$EnhancerByGuice$$653209545{type=proxy, format=docker, name='remote.docker.repo'}

2022-10-19 20:13:26,646+0000 DEBUG [qtp2044915405-391638]  service-jenkins org.sonatype.nexus.repository.docker.internal.orient.DockerProxyFacetImpl - Fetching: GET https://remote.docker.repo/v2/prod/another-namespace-here/payment/manifests/3.34 HTTP/1.1

2022-10-19 20:13:26,652+0000 WARN  [qtp2044915405-391638]  service-jenkins org.sonatype.nexus.repository.docker.internal.DockerFacetUtils - Could not parse error response Unexpected character ('<' (code 60)): expected a valid value (JSON String, Number, Array, Object or token 'null', 'true' or 'false')
 at [Source: (ByteArrayInputStream); line: 1, column: 2]

2022-10-19 20:13:26,653+0000 WARN  [qtp2044915405-391638]  service-jenkins org.sonatype.nexus.repository.docker.internal.orient.DockerProxyFacetImpl - Exception org.sonatype.nexus.repository.docker.internal.V2Exception: access to the requested resource is not authorized checking remote for update, proxy repo remote.docker.repo failed to fetch v2/prod/another-namespace-here/payment/manifests/3.34, content not in cache.
org.sonatype.nexus.repository.docker.internal.V2Exception: access to the requested resource is not authorized

Not sure if the problem is with my auth OR the Unexpected character error OR other.

Thanks for any assistance.

Figured out our issue. Network.

We had to add the remote hostname to Hosts to Exclude from HTTP/HPPTS Proxy in the System > HTTP settings of Nexus (which was running inside a container)

The Unexpected character error was a red herring.