[OS X Emacs] problem with updating packages

[Johannes Brauer]

Hi!

Using list-packages and mark all available upgrades 

22 packages marked for upgrading.
Upgrade these 22 packages (cider-0.25.0, clojure-mode-20200419.559, clojure-mode-extra-font-locking-20200320.823, company-20200616.2354, dash-20200524.1947, ediprolog-1.2, magit-20200713.2103, markdown-mode-20200715.1516, org-re-reveal-20200705.822, org-ref-1.1.1, rainbow-delimiters-20191018.1233, async-20200113.1745, flycheck-20200610.1809, git-commit-20200701.2112, helm-20200720.1510, helm-core-20200720.1510, htmlize-20191111.2130, ivy-20200624.1140, js2-mode-20200610.1339, org-20200720, transient-20200719.955, with-editor-20200617.1234)? (y or n) y

Trying to upgrade these packages the following error message is shown:

Package menu: Operation started [Upgrading 22]
package-install-from-archive: Wrong type argument: stringp, nil

In my Preferences.el I have th following configuration:
(require 'package)
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/") t)
(add-to-list 'package-archives '("org" . "https://orgmode.org/elpa/") t)
(add-to-list 'package-archives '("gnu" . "https://elpa.gnu.org/packages/") t)
(package-initialize)

I am using Aquamacs 3.5  GNU Emacs 25.3.50.1 (x86_64-apple-darwin16.7.0, NS, macOs 10.15.7

I have no idea what I could do. Any help?

Johannes