I'm trying to push an xlsx file to a remote repository using git LFS. 

I've tried two ways: Using Sourcetree click-thru menus and using the terminal server. Both result in the same error message. 

I set up a remote repo in Bitbucket and set the Allow LFS option. I cloned the empty repo to a local file location. 

In Sourcetree, I used Repository/Git LFS/Initizalise repo. This gave me a click-thru menu to set up a gitattributes file, which I set to allow xlsx files (\*.xlsx) . I committed and pushed the gitattributes file which was automatically created. Then I moved the Excel file into the local folder, committed, and tried to push.

In the terminal window, I used much the same approach--cloning the empty remote repo, then doing git lfs install, git lfs track "\*.xlsx", committing and pushing the gitattributes file, and then adding and committing the Excel file. 

When I tried to push in either Sourcetree or using the terminal, I got the same error message:

```sh
Uploading LFS objects:   0% (0/1), 0 B | 0 B/s, done
Fatal error: null
error: failed to push some refs to 'remote_repo_location'

git clone remote_repo
cd remote_repo
git init
git lfs install
git lfs track "*.xlsx"
git add -A
git commit -m "test"
git push origin master 

(this works fine and puts the gitattributes file in my remote repo)

Then I physically copy the Excel file into the folder and do this:
git add -A
git commit -m "test2"
git push origin master

```

This causes the error message