After upgrade to MacOS Mojave, I cannot login or connect to App Store.

Like everyone else, I am experiencing the same issue, and all of the recommended fixes haven't worked. I've been experiencing this for about 2 months now, and have a bunch of outdated apps because I can't log in to update. Calling Apple and having them do simple things like resettings SMC and reinstalling the OS using the recovery partition didn't help at all!

I just spent an hour and a half on the phone with Apple Support. They are aware of the issue. The advisor walked me through a few steps, but the problem remains. I submitted logs and a packet trace. I'll post here if/when the problem is resolved.

I am having the same problem. Contacted support spoke to a supervisor who couldn't get it working for me. He then had me download an app to collect data from my iMac. He contacted the engineers and they are working on it. I hope to hear back on Wednesday. If not I will try cmd-R and restore Mojave.

Don’t waste time on restore. It won’t work. People in this thread already tried.

What will work if you’re in desperate need to update apps is to create a new user on your Mac and use the same AppleID.

Tried that, when App Store app was dragged to the AppCleaner I received a message saying "This application can't be deleted as it is required by MacOS". I will find another app and try that if possible.

I tried that using AppZapper and did exactly what you suggested.

Didn't work for me. Although the initial welcome screen displayed telling me about the new Mac App Store, signing didn't work and when I tried to install an app, I just got the same alert saying "cancelled".

I had this same error message ("in use by macOS") and was able to resolve it by disabling SIP using the above steps. Give that a try and see if you can delete them then.

I'm currently at the same stage as brendanfromab above—apps won't download and the error message is "cancelled"—so, not quite solved yet. Good luck!

Yeah, it looks like there are multiple issues going on here. I don't run the software firewall on my Macs, I leave that. to the firewall in the AirPort Extreme Base Station. IPV6 isn't an issue for me, as my provider doesn't support it for residential customers, only business. So just thinking what might have been different between my setup and others here that prevented the fix.

I did an in place upgrade over high Sierra. late 2015 27" iMac 32 GB RAM, 2TB Fusion drive. Something that did go well for me that I was wondering if it would or not, is the Fusion Drive was converted to APFS from HFS+ with no issues on Mojave upgrade. This was a question, because Apple pulled Fusion Drive support from High Sierra for APFS.

So, considering this was the only issue I had to resolve.

In general Mojave creates the APFS for the SSD part of the fusion drive and standard format for the HD portion. That is what I have. If you look at the system report you will see that configuration in the SATA drive area. I tried the above posters method and downloaded a drive cleaner. But alas no luck still can't login. I have reinstalled Mojave from the CMD-R no luck. It is up to the engineers. I might install Beta 1 and see what happens if Wednesday bears no fruit.

I really hope you guys get issues sorted soon, I've had minimal issues and as I've said I've resolved all I can, the others remaining in my case are App issues, which I've been in communication with the developers for, and really, it's only one pice of software, and the issue is minor, and doesn't affect daily use of the system.

I do feel for those on this thread, and others I've read that are having issues. I've beta tested for Apple the last few os releases, and know what kind of issues that can come up. Since I didn't really have any issues with Mojave, that weren't easily fixed, I had my hopes more people would be able to experience a problem free upgrade this time around. At least, more so than the last couple versions.

So I got tired of waiting around for a response from Apple. Luckily, my wife owns two MacBook Airs, one for home and one for work. I waited to update the work machine because it was having some other issues. So today in short I restored my wife's home MacBook Air that was having the issue from Time Capsule backups of her work one that has no issues with the App Store. All I had to do is make some minor tweaks with some software installs and uninstallation, but all is good now. So if you have another Mac and want to try this, it should work!

I wanted to double check my system for the "Previous Content' folder a poster posted several posts above, just to make sure I didn't have any left over stuff, even though my App store is working. The issue is, they didn't leave the path to where the folder was, and Google didn't bring back any results of a folder with that name regarding macOS.

Where was your Previous folder located with the other version of the App Store? It's not in my Applications folder, or root of the hard drive, or any other typical place I've searched.I initiated the command to create the locate database, so I'll use that in a bit, but if you could give any feedback on where you found the mentioned folder, would be appreciated.

Thanks.

Thanks, I guess my upgrade got cleaned up correctly. I didn't have this folder. I also only have one copy of the Mac App Store. Everything's been a cool breeze here, ever since I cleaned up the App Store, and reset it to defaults by removing the files I mentioned in an earlier post.

One other note, while I use the App Store for some of my items, I really prefer to buy directly from the developer when possible, usually makes things easier to manage, and they are free to include features apple's App Store policies prohibit.

I'm also having this problem. It started when I downloaded the beta of Mojave and persists through the release. If you open Console, you should be able to start to diagnose what is causing the error, although I haven't been able to fix it yet. I have reported it to Apple and hopefully a future update will resolve it.

Here's the code that I've found in Console for my issue. As you can see, there appears to be two different instances of the files that would authenticate my sign in. Unfortunately, they're owned by Root and can't be deleted, changed or renamed. Ironically, the sign in credentials seem to be accepted because if I use the wrong credentials it rejects them. Even with the right sign in, I always see Sign In in the lower left and in the menu, and I'm unable to purchase items or to upgrade existing applications.

Sep 25 07:26:13 Rons-MacbookPro-3 App Store[2783]: DEPRECATED USE in libdispatch client: dispatch source activated with no event handler set; set a breakpoint on _dispatch_bug_deprecated to debug

Sep 25 07:26:21 Rons-MacbookPro-3 App Store[2783]: objc[2783]: Class ITNSImage is implemented in both /System/Library/Frameworks/iTunesLibrary.framework/Versions/A/iTunesLibrary (0x7fff86114568) and /System/Library/CoreServices/SetupAssistantPlugins/iTunes.icdplugin/Contents/Ma cOS/iTunes (0x11f5567c8). One of the two will be used. Which one is undefined.

system.log. You can leave Console open as you try and log in and watch it update the log with any error it encounters. Note the time before you log on so you can easily isolate the entries. Alternatively, you can search on App to find the related entries.