Failed to verify code signature of /private/var/installd/Library/Caches/com.apple.mobile.installd.staging/temp.XhVlHm/extracted/AltStore.app : 0xe8008001 (An unknown error has occurred.)
Same problem here, is there a workaround?
IOS 13.3.1
almost the same when installing altstore windows
but instead 0xe8008018 (The identity used to sign the executable is no longer valid)

Not Working For Me Too.
I Reinstalled AltStore And This Happened.
This issue should be fixed on the latest versions of AltStore/AltServer. Closing this issue.
Still not fixed on the latest version
@vamgan Please provide the following information if you can:
Are you having the exact same issue as @hbbxmjbb? Lastly, can you try uninstalling AltServer and using the latest beta AltServer.
Exact same issue
Windows 10
Installed and reinstalled many times the latest version: 1.3.2 beta 3
Also having this issue on latest version 1.3.2, iPhone 7 13.5 on Windows 10
Please try deleting the “adi” folder in iTunes’ file directory, then restart your computer and try again.
The first time I attempted it, AltServer exited while "installing" without any error prompt. I tried it a second time (after deleting the file again and restarting) and it continues to give me the same error. The file reappears after each reboot. I've already restored my phone, tried a new Apple ID, reinstalled ITunes/ICloud a few times, disabled my firewall, and a few other things.

Please make sure that your iOS Time + Date and Windows Time + Date are correct and in sync. This should fix your issue.
Solved! I guess my BIOS never had its system time set correctly and this managed to solve it after enabling automatic time setting, automatic timezones, and syncing with windows again. Thank you for the help, this was extremely frustrating.
If you have Reprovision installed try downgrading it to previous version or uninstall it..downgrading worked for me..:)
Using win7, time is correct, checked, synced once more, but didn't helped me, still have error: "Failed to verify code signature of /private/var/installd'Library/Caches/com.apple.mobile.installd,staging/temp.4TdWwd/extracted/Altstore.app : 0xe800800d (There was an error communicating with your device.)" Altstore installing perfectly on my SE, but it is not installing on my 5S.
Update: cleared iPhone data and restored it from iCloud. Altstore installed on 5S
Sorry @cdK1337 what exactly do you mean by "cleared iPhone data"? Did you restore the phone, or use one of the options in the Reset menu? Or was it on the Mac side? I'd appreciate if you could elaborate a bit :)
Hello @halfbrilliant I cleared all iPhone data from the options in reset menu, so the phone was like new. I was using windows 7. Don't remember how I restored all data - from windows or from options on the phone, I don't remember, but, probably, when the phone turned on, it suggested me to restore all data from iCloud.
i just got the same problem

Most helpful comment
Please make sure that your iOS Time + Date and Windows Time + Date are correct and in sync. This should fix your issue.