Are you using ob-ipython? Your trace makes it seem like that might be loaded maybe in your init files. This issue seems to cover the problem you are having, since it says that it's modifying `org-mode-hook'.
https://github.com/gregsexton/ob-ipython/issues/161 Maybe since you have a clean install you're missing jupyter while you weren't before? On Wed, Sep 16, 2020, at 16:56, Uwe Brauer wrote: > Hi > > I freshly installed Ubuntu 20.04 and used the pre compiled Emacs 26, I > copies also all my init files. > > When I open an org file I obtain an error message I don't understand and > attach any help is appreciated > > Regards > > Uwe Brauer > > > Attachments: > * bug
