I opened another thread here since it seems to be a problem not only with my app, but also with all other apps downloaded as .dmg file: https://developer.apple.com/forums/thread/706210

Thank you Quinn! I read all the articles and found a partly solution in my other thread. Read you there :)

Problem solved, see other thread :)

Notary service is down again for 12 hours now. What's going on there?

Still not working, since 15 hours. Same http 500 error message for xcrun notarytool history …credentials…

According to the license terms, the App Store Connect API seems to be usable only for internal development purposes, not for providing apps that are going to be published. So even if this is technically working it is not legal, isn't it?

Problem is that altool seems not to part of the xcode command line tools that I installed some days ago via "xcode-select --install". Since the notary service via app-specific password is still out of order (and it is unclear if and when apple will fix it?): What is the correct way to install altool besides the xcode command line tools that I already installed?

@Quinn, did escalating help? I additionally contacted the Apple Developer support (by e-mail since there is no option to get a phone call). In hope of an answer coming soon...

Hm, when I want to use the App Store Connect API the first time I have to agree to the following (sorry, its in German, I tried to get that text in English but I didn't find out how to do that): "Indem Sie dieses Markierungsfeld aktivieren und auf „Übermitteln“ klicken, stimmen Sie zu, dass Sie die App Store Connect-API nur für die interne Entwicklung, das Testen innerhalb Ihres Teams, zu Berichtszwecken und nur gemäß der Dokumentation verwenden.". So, for me this means roughly that this API may only be used for internal development, tests and reporting, according to the docs. To which of these types would you assign the notarization of apps that will be published?

Works for me as well. Thanks for fixing!

Ok, that sounds plausible. If notarisation service won't work again at any time in the future, then the App Store Connect API approach would be the way the go for us.