Some users have written that they are having app store issues after updating to macOS Mojave. The most common error messages related to the issue are “An unexpected error occurred while signing in” followed by the “cannot connect to app store.”
The other error that shows up sometimes for users occurs when they are trying to download an item from the store. This error shows up as “Your purchase could not be completed, cancelled.” Trying to view your account shows the “Cannot connect to app store” message from here.
The first of these issues is probably related to some kind of conflict when it comes to the app store credentials files.
When you open the App store on your MacBook running macOS Mojave, the app opens up just fine, showing that you are logged in with your credentials (on the bottom left of the screen) while displaying the Sign-in window to start downloading updates or browse the store.
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The error sequencing starts to happen once you enter your credentials on this sign-in screen.
Before you proceed with the detailed troubleshooting steps below, try to sign-out of your App Store account as well as your iCloud account. Restart your MacBook and then sign back in with your credentials to see if that solves the app store problems that you are experiencing.
Sometimes the simple sign out and sign back in with a restart of the machine can do the trick.
Please follow the steps below you couldn’t resolve your issue via the simple restart/sign-out/sign-in process.
How to Fix App Store Sign-in Issues on macOS Mojave
What has worked for some is to check their MacBook for redundant copies of the app store application and delete them from their machine. Redundant copies may exist on your machine via carbonclone copy or older backups of the app.
- In order to check this, you can start by clicking on the > About this Mac > Overview > System Report.
- Next, choose Software on the left panel followed by Applications. Give it a few minutes and the list of applications will load on the right hand side of the screen.
- Scroll down and locate “App store”. You should only see one copy of the App Store here. Clicking on the line, will show you the location of the Application on your MacBook.
- If you have multiple copies of the app store app on your MacBook, you will need to delete the redundant application copies and restart your MacBook and try signing into your App Store.
The other common reason for connection error on the macOS App Store is often related with incorrect system date/time information as explained in this Apple whitepaper. Follow Apple’s guidance and check out the System date/time settings on your MacBook.
Cannot Connect to App Store on macOS Mojave
Check your Trust Certificates on macOS Mojave
Some users have had some success with re-establishing their trust certificates on their MacBook in order to circumvent this issue. Make sure to backup your MacBook before your use the following:
- Open Finder and go to ‘/Library/Security/ Trust Settings’ folder
- Copy this folder to your desktop so that you have a copy
- Remove any preference list files that you have in this folder by dragging them out to your desktop.
- Restart your MacBook and try signing in back into the App Store
- If it does not work, you can move the plist file back into the ‘/Library/Security/Trust Settings’ folder
- The other security certificate to check is the ‘Digicert High Assurance EV root CA”
- Open up keychain access utility using spotlight
- Click System Roots on the top and click certificates on the bottom window
- Locate and double click ‘Digicert High Assurance EV root CA”
- Click on ‘Trust’ to expand it
- Change the “When using this certificate” to “Never Trust”
- Restart Your MacBook
- Follow steps 6 through 10 above again and change it back from ‘Never Trust’ to “Use System Defaults”
- Check if you are able to connect and access the App Store
Getting Error 500 message after entering credentials?
Some users have reported that when they try and sign in into the App Store, they get a weird 500 error message that is associated with com.apple.commerce.client. Restarting the MacBook and cleaning up plist files didn’t help much with the issue.
The only workaround that seems to be working is via Terminal. Open up the terminal utility on your MacBook and type in the following command:
defaults write com.apple.appstore.commerce Storefront -string \ “$(defaults read com.apple.appstore.commerce Storefront | sed s/,8/,13/)”
Restart your MacBook and then try accessing the Appstore with your credentials.
How to Fix ‘Purchase Could Not be Completed Error’ on macOS Mojave
If you have no issues with signing in and accessing the macOS App Store but having issues with downloading items, this could be very well be related with ‘plist’ files on your MacBook for the AppStore.
There are a few key App Store files that you will need to locate on your MacBook. Sometimes these preference list files get corrupted and can cause issues with the App Store experience on macOS Mojave.
The 3 key files to look for and delete from your MacBook are the following:
For sandboxed apps, as in this case, you will be able to locate these files in your user library.
- Start by opening up the Finder app on your MacBook
- From the top menu, click on ‘Go’ followed by ‘Go to Folder..’ and type in /~/Library/Containers/com.apple.appstore as shown below
- Expand the Data folder followed by Library and then Preferences
- Here you will find the three files that need removing.
- You can drag these files out to your desktop for now
- Next, Restart your MacBook and try signing in and downloading an item from the app store
- If you are successful, you can go back to the desktop and move the plist files into trash
If the steps illustrated above do not work for you, you can try installing a fresh copy of macOS Mojave on your MacBook or reach out to Apple Support as they will be able to help with this issue.
We hope that you found these tips helpful. Please let us know in the comments below if you have any questions.
Obsessed with tech since the early arrival of A/UX on Apple, Sudz (SK) is responsible for the original editorial direction of AppleToolBox. He is based out of Los Angeles, CA.
Sudz specializes in covering all things macOS, having reviewed dozens of OS X and macOS developments over the years.
In a former life, Sudz worked helping Fortune 100 companies with their technology and business transformation aspirations.