up vote 35 down vote favorite
20

I just upgraded GNU Emacs from 23 to 24 on MacOS and some ELPA installed packages stopped working. One of them is AucTeX. Deleting it and reinstalling it through the package manager made it work again, but I don't want to do this by hand for every package. I'm slightly confused that I find nothing about that on the Internet.

Don't the .elc need to be recompiled for a new version of Emacs? Why isn't this a feature of package.el?

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up vote 64 down vote accepted

You do not need to re-install all packages. The packages itself are likely fine, however, they need to be re-compiled, because Emacs Lisp byte code is generally not compatible across major versions.

To re-compile all packages, type M-: (byte-recompile-directory package-user-dir nil 'force). After restarting Emacs, packages should work fine again.

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  • My understanding is that byte code compatibility is only an issue if you are downgrading (or similar) to an older major version of Emacs. A newer Emacs version will run byte code compiled by an older Emacs version. – phils Oct 27 '16 at 0:02
  • 1
    While it is true that emacs byte code maintains backwards compatibility, it is usually a good idea to re-compile, especially when moving to a later major version. The reason is that later major versions often introduce new features and some of these can result in improved performance or functionality. – Tim X Oct 29 '16 at 3:14
up vote 3 down vote

The variable package-activated-list holds the list of packages we're interested in. So we just need to install each one again. We don't need to explicitly delete them; calling package-install will blow away an old version.

Put this code in a scratch buffer and evaluate it (that is, put your cursor at the end, and press C-x C-e):

(dolist (package-name package-activated-list)
  (package-install package-name))
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  • This fails: Debugger entered--Lisp error: (wrong-type-argument arrayp ac-dabbrev): line 1: package-desc-full-name(ac-dabbrev) line 2: package-install(ac-dabbrev) – Ian Kelling Jul 20 '15 at 17:12
up vote 1 down vote

This works for me on Emacs 25.1 and 26:

(defun package-reinstall-all-activated-packages ()
  "Refresh and reinstall all activated packages."
  (interactive)
  (package-refresh-contents)
  (dolist (package-name package-activated-list)
    (when (package-installed-p package-name)
      (unless (ignore-errors                   ;some packages may fail to install
                (package-reinstall package-name))
        (warn "Package %s failed to reinstall" package-name)))))
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