We could not complete your purchase. in App Store

I called support and ask this issue. And they say; There is no problem on your Apple Account please check your default payment method sometimes it may cause this type of problems. And I tried 3 different working Credit Cards and still nothing. (MacBook Air Late 2017, OSX 10.14.6).

Ask for assistance here: Get Support

Keep calm and carry on. This seems to affect Mojave systems only, and no doubt Apple will fix it sooner (sigh) or later. The problem will not be solved by re-installing Mojave or by any other suggestions put forward by Apple support.

Exact same problem on my 2017 MacBook Pro macOS Mojave 10.14.6. All apps can't purchase and update. Has been gone through with Apple Support with all debugging steps, rebooting, safe mode, reset router, delete files etc. At the end, transfer the call to App Store supervisor and she would need few days to feedback to back-end team and get back to me... What?!!

Apple, if you listen here, please solve this problem ASAP!

[Personal Information Edited by Moderator]

Same here. I really don't want to update to Catalina yet since I have important 32 bit apps.

Don't bother trying to boot in safe mode. I tried on 3 different machines (MacPro 5,1 and MacBook air) and it does not solve the issue. Same error when in safe mode. Hope this helps.

Sorry I cannot help as I have same issue too. MacPro 5,1 running 10.14.6 and previously installed apps wont update, clearing caches, signing out, reseting DNS etc all do not work. I cannot even get a new app that have never owned or downloaded.

Started happening couple days ago, but no updates were installed or applied, was eventually able to update some installed apps asking for updates by multiple tries then, today simply cannot update.

Tried deleting app and redownloading and now cannot even do that even though the download from cloud icon is showing indicating that the app has been purchased before.

I suspect its back end issue as there are many reports popping up today 20 May 2020

Same problem here, though the funny (or maybe not) thing is that it only occurs on my “obsolete” Mac Pro 5,1 (2010; Mojave). On a Macbook Pro (also from 2010 with High Sierra) I can download apps from App Store, and also on an iPhone 6S.

Have tried a re-install on the Mojave machine. No joy.

Same issue for me. I reset both my SMC and PRAM but have the same outcome. I can't boot up in Safe Mode (due to encrypted HW) to test that out.

I can't move to Catalina due to corp requirements requiring some 32-bit SW.

Mojave App Store no downloads or updates, "We could not complete your purchase". Since yesterday, no downloads or updates.

This is happening on both my Mojave iMacs, but my old iMac with High Sierra and the old App Store and by the look of it iPhone and iPad are fine.

It seems to be just the Mojave App Store with me and as the other OS's are fine, my account can't be the problem.

Been driving me mad!

All is now well again in the Apple world - until the next time!

Separate subject (and there is/was a different thread) my MacBook Pro 2018 was seriously overheating and fan running continuously after Catalina 10.15.4. I downgraded to factory settings High Sierra then up to Mojave and all is fine again, everything cool as a cucumber. I repeated this cycle to check with exact same results. Must be the 10.15.4 upgrade, Anyone else having this issue ?

Happening to me, too, on 2 different Macs running Mojave 10.14.6. However, I am able to download a past purchase on my Catalina Mac.

Submitted email to support, but no resolution yet.

No problem on my Ipad either, only happening on my Macbook since i updated to Mojave yesterday !!

So this could be a Mojave-only problem?