We could not complete your purchase. in App Store

I am having that same problem as well -- signing in to this forum as well as appleid.apple.com doesn't give me the box to enter the code.... except on Safari on the Mac. Any other browser on the Mac or Windows 10 - it sends the code to my devices but there's no box to enter it and it immediately says it failed. HOWEVER, it just worked a few minutes ago on Chrome!

Had to call Apple support. The wait was too long and I had to go to a meeting before talking with the Mac App Store team, but when I finished my meeting... everything was working again.

My suggestion: Call 1-800-275-2273

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 ?

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

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.

I only updated to mojave so i could get the logic pro update, didn't want to chance catalina on my 2012 macbook pro.

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?

It's looking that way

Same situation here. Updating to Catalina is not an option for me because of important 32-bit software.

me too.

Not only for US accounts. My Japan account and Taiwan account have the same problem.

I login logout App Store, reboot, clean NVRAM... many many times not fix.

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.

Same problem. Upgrading to Catalina isn't option for me too