Cannot open file with “#” in the filename in version 7.4.1

[krassowski]

After I upgrade my jupyter notebook to version 7.4.1, in traditional notebook mode, cannot open file with “#” in the filename, and there is a “file not found” error. It seems that the full filename isn’t passed when there is “#” in the filename.

But the same file can be opened in the jupyterlab mode, and in some very old version, there is no such problem.

Originally reported by winoenix in https://discourse.jupyter.org/t/cannot-open-file-with-in-the-filename-in-version-7-4-1/35426/2, reproduced by another Jupyter contributor as per the linked thread

[andrii-i]

I can reproduce this in 7.4.3 on MacOS in Firefox.

Suggestion from triage on next steps of troubleshooting this issue: check file opening code in JupyterLab vs Jupyter Notebook, specifically part that escapes special characters.

Notebook URL when opening a file with "#" in the filename:

JupyterLab URL when opening a file with "#" in the filename: