We have several reports, that in rare cases, docker pushes to NXRM hosted repos may fail with messages similar to:
28f6517e2463: Layer already exists
128dd347f60c: Layer already exists
d9ff549177a9: Layer already exists
e1a204bf4760: Layer already exists
blob upload unknown
##[error]blob upload unknown
##[error]/usr/bin/docker failed with return code: 1
This appears to occur when two zero byte chunks for two different layers are uploaded to the same image namespace at the exact same time. Predicting when this could happen is near impossible.
The only workaround at this time is to repeat the same docker push - in the case of CI builds this is especially troublesome, but has been reported to workaround the initial failure.