I cant install altstore on my iPhone XS with iOS13.5
First I get this message:
AltStore already installed on another device.
Apps installed with AltStore on your other devices will stop working. Are you sure you want to continue?
Then I see this error:
The operation couldn鈥檛 be completed. Cannot activate more than 3 apps and app extensions....
If you are running iOS13.5.....

Offload Unused Apps is disabled. I have currently no other apps activated on my device. A few months ago i installed altstore, but its deleted long ago.
I tried three different Apple IDs always with the same error.
Is there any way to see or delete this ghost apps?
I'm running altserver on MacOS Catalina v10.15.4.
Thanks for helping.
I have the same issue!
macOS Catalina, v10.15.4 (19E87)
AltServer Version 1.3.2 (24)
iOS 13.5 on my iPhone 7
Mail plugin "Bundle version" = 1
I have 2-factor auth on my icloud account.
I've installed altstore a couple of months before this but I've deleted it,
disabled offloaded apps.
No 3rd party apps are on my system.
Before I install I get this warning:

Maybe it could be counting PWAs, or web shortcuts on the home screen as an installed app? Or maybe there could be some ghost apps.
Hi!
You just need to remove all offloaded apps in your iphone.
After this, try again.
I dont have any offloaded apps.
Offload apps is disabled and was never enabled
Hi!
You just need to remove all offloaded apps in your iphone.
After this, try again.
OK. For any reasons I had 4 Offloaded apps (Apps on Homescreen with cloud symbol). I deleted/reinstalled them and now its working.
Thanks a lot
I went through my home screen and couldn't find any offloaded apps. I think the issue might have been that I had deleted some of the stock apps. After reinstalling the stock apps it works.
I am the same as @JosephDuffy - I haven't offloaded any apps, but I have deleted some stock apps, and I get this error.
Edit: I get an error from the AltStore app when attempting to install a 4th app, not from the server when trying to install AltStore.
Is there a full list of stock apps? Or is there a way to see all of the
offloaded stock apps?
I can confirm that after downloading all of the stock apps, I was able to install AltStore on my device! If this is true across the board, we should edit the error message to something like the following:
"The operation couldn't be completed. Cannot activate more than 3 apps and app extensions.
If you're running iOS 13.5 or later, make sure "Offload Unused Apps" is disabled in Settings > iTunes & App Stores, then install or delete all offloaded apps to prevent them from erroneously counting toward this limit. Stock apps that have been deleted also count toward this limit, so make sure that all stock apps are downloaded."
I have all the stock apps installed but I still can鈥檛 get it to work maybe I have to change iTunes reigion
Checked but no apps were missing still doesn鈥檛 work
If you are using macos, here is solution - https://stackoverflow.com/a/61978102
If you are using macos, here is solution - https://stackoverflow.com/a/61978102
Using windows any workaround?
Make sure Automatic sync is enabled in Finder.
Open Fider->Select iPhone->General->Check Automatically sync when this iPhone is connected.
This resoves the issue.
Using windows any workaround?
Try the same for iTunes for windows, hope this would work for you as well.
Using windows any workaround?
Try the same for iTunes for windows, hope this would work for you as well.
It is enabled
Has anyone figured this issue out? I am still having this issue
Most helpful comment
I can confirm that after downloading all of the stock apps, I was able to install AltStore on my device! If this is true across the board, we should edit the error message to something like the following: