I am having this same issue now... App was working fine a few days ago and was able to push and make changes without any problems. I can still access the apps info through the CLI (start, stop, logs, etc) but I can not push any updates to the nodester git.
At first on the git push origin master, it would just hang, but now it is returning this error? Any ideas of what the issue is, or how I might go about solving this?