It can be caused by large files in your repo. Github has 100 MB limit for a single file in a repo. You might want to check it by using git lfs migrate info
.
I've had the same issue but this particular error was intermittent. I occasionally have seen "error: GH001: Large files detected. You may want to try Git Large File Storage". Also when I switched to SSH for remote origin instead of HTTPS it gave me broken pipe error message.
I already used LFS but my .gitattributes missed some large files so I've updated it and run git lfs migrate import --include="*.fileextension"
then pushed to github without an error. See https://help.github.com/articles/moving-a-file-in-your-repository-to-git-large-file-storage/.