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

I'm not a expert, but open finder go to your Macintosh HD then click on Library then Security Then Trust Settings. Let me know what is or isn't in there. Also in Security is there a zip file.

Right click the App Store and screen shot the info that pops up.

in the last software update (10.14.2) the problem is solved

Hi there, brianyen0!
Thanks for reaching out to the Apple Support Communities! It sounds like you have an issue with connecting to the App Store on your Mac and I’m happy to assist. I recommend checking out this article with steps to follow If you can't connect to the iTunes Store, iBooks Store, or App Store. This article will give you the best troubleshooting steps to take, along with the next steps to take if the issues continue.
Have a wonderful day!

Does that actually show a Debug menu on Mojave? When I perform those steps, there is no Debug menu.

$ defaults write com.apple.appstore ShowDebugMenu -bool true

$ defaults read com.apple.appstore

{

...

ShowDebugMenu = 1;

UserSetAutoPlayVideoSetting = 0;

mostRecentTabIdentifier = discover;

}

[Open App Store]

$ defaults read com.apple.appstore

{

...

UserSetAutoPlayVideoSetting = 0;

mostRecentTabIdentifier = discover;

}

[ The ShowDebugMenu setting is no longer present ]

Hello..I was getting the same problem. But my App Store is working now after update for two apps became available. I test opening and closing the app and still able to access/connect App Store.

Thank you.

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!

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.

Neither using my Admin account or signing in, in Safe Mode, worked for me. It looks like I'll have to wait for Apple to fix this problem. I'm convinced that in my case, there are remnants of the old App Store on my drive that for whatever reason were not cleaned up during the installation process.

Reinstalled macOS and have the same

exact issue. I’ve tried all suggestions posted in this forum and have not resolved the issue. It seems like the only option is to do a clean install, restore files from back up and not restore system settings. I think that’s overkill because it seems like a networking configuration issue on the app side that might be resolved by fixing a file or configuration setting.

 needs to address this since it seems like a common bug.

Stefanspk wrote:

We had exactly the same problem after we upWe are all connected over ethernet and this morning I disconnected the ethernet and opened up a personal HotsSpot on my iPhone- and now the App Store is back to life..!

Tried this immediately just seeing your post - no luck unfortunately. Same behavior with personal hotspot as with ethernet and wifi.

b33rg33k wrote:

So this is a network related issue with the App Store and network port configuration. Funny that so many folks can replicate the issue but we have yet to hear from  Support on a quick fix. Does anyone know what ports the App Store uses when it's connects to Apple's servers?

Yes, I've looked at it. The app store mostly uses 443/tcp, but I don't believe that's the issue. In my case there is no actual network connection attempted that I've been able to detect when signin fails.

Like some of the posters a few pages back I suspect an issue with certificates that are causing the SSL connection to fail before a TCP packet is even sent, but have not had any luck figuring out which exactly and where.

macnewED

The plist files that are removed will be regenerated the next time they're required by an application. There's either some sort of corruption or contradictory line of code in those files that was causing the problem.

Apple prioritizes their focus first on items that crash the system or cause kernel panics, then start down the list from there. I've been beta testing Mojave for months, and this problem has been there since I started. It doesn't appear to be too wide spread since, on the developers forum, I was the only one reporting the problem. Once Mojave went into wider release, it started to affect more people and hence it got their attention.

I am proud and grateful for all the ideas. I now can open the app store. Following the lead from Mr Gertz above, I discovered that I had three app store applications on my computer . One was buried in a folder on my desktop, and on was found by going through my old hard drive accounts looking for a comparable date, which I did.

So all is well (right now). Thanks to all.

I tried to post this earlier but must have erased it:

Open the app store app. Look up at the top of the page and your will see "store".

Click on store and scroll down to the bottom of the dropdown and open "view my account"

You will see many of your apps if not all.