GitHub pencil (Edit) button disappears

Question

I have a GitHub repository where I put my jupyter notebooks in it. While I open my notebooks in GitHub, I usually see a pencil button where I can Edit my notebook:

However for some other notebooks in the same repository it disappears:

Why this happens and how to fix it?

Answer 1

It is simply because of the size of the file. Github does not allow editing large files (not sure what is the exact size limit) It sometimes even restricts viewing such files, and they can be viewed only in the raw mode.

To edit these files, edit them in your local clone and push them to the desired branch using git cli, Github Desktop, SourceTree etc.

Edit: Answer is outdated now. Please see the workaround mentioned in comments.