1Password was unable to complete installation - Windows 10

I was hitting this same problem, both when updating 1Password, and when trying to reinstall it. This is on Windows 11.

The fix for me was to add a Microsoft Defender exclusions for %localappdata%\1Password. Here's the installation log for a failing attempt:

INFO 2024-01-25T19:34:27.762 main(ThreadId(1)) [1P:op-windows-starter\src\installer.rs:621] Setup logs path set to : C:\Users\$USER\AppData\Local\1Password\logs\setup
INFO 2024-01-25T19:34:27.768 main(ThreadId(1)) [1P:op-windows-starter\src\installer.rs:78] executing C:\Users\$USER\Downloads\1PasswordSetup-latest.exe, build 81024044
INFO 2024-01-25T19:34:27.768 main(ThreadId(1)) [1P:op-localization\src\lib.rs:239] system locale detected as 'en-US'
INFO 2024-01-25T19:34:27.768 main(ThreadId(1)) [1P:op-localization\src\lib.rs:265] selected translations for EN_US based on detected locale en-US
INFO 2024-01-25T19:34:28.719 main(ThreadId(1)) [1P:op-windows-starter\src\installer.rs:536] Starting fresh install to 81024044
INFO 2024-01-25T19:34:28.910 main(ThreadId(1)) [1P:op-windows-starter\src\installer.rs:302] Copying files to C:\Users\$USER\AppData\Local\1Password\update
INFO 2024-01-25T19:34:28.910 main(ThreadId(1)) [1P:op-windows-starter\src\transaction.rs:71] copying files to: C:\Users\$USER\AppData\Local\1Password\update\8
INFO 2024-01-25T19:34:30.387 main(ThreadId(1)) [1P:op-windows-starter\src\installer.rs:306] Renaming C:\Users\$USER\AppData\Local\1Password\app to C:\Users\$USER\AppData\Local\1Password\previous
INFO 2024-01-25T19:34:30.387 main(ThreadId(1)) [1P:op-windows-starter\src\transaction.rs:128] renaming C:\Users\$USER\AppData\Local\1Password\app to C:\Users\$USER\AppData\Local\1Password\previous
INFO 2024-01-25T19:34:30.550 main(ThreadId(1)) [1P:op-windows-starter\src\transaction.rs:171] renaming C:\Users\$USER\AppData\Local\1Password\app to C:\Users\$USER\AppData\Local\1Password\previous
INFO 2024-01-25T19:34:30.550 main(ThreadId(1)) [1P:op-windows-starter\src\installer.rs:310] Renaming C:\Users\$USER\AppData\Local\1Password\update to C:\Users\$USER\AppData\Local\1Password\app
INFO 2024-01-25T19:34:30.551 main(ThreadId(1)) [1P:op-windows-starter\src\transaction.rs:171] renaming C:\Users\$USER\AppData\Local\1Password\update to C:\Users\$USER\AppData\Local\1Password\app
ERROR 2024-01-25T19:34:30.552 main(ThreadId(1)) [1P:op-windows-starter\src\transaction.rs:57] failed to rollback rename of C:\Users\$USER\AppData\Local\1Password\app to C:\Users\$USER\AppData\Local\1Password\previous. Error: Os { code: 2, kind: NotFound, message: "The system cannot find the file specified." }
ERROR 2024-01-25T19:34:30.554 main(ThreadId(1)) [1P:op-windows-starter\src\transaction.rs:51] failed to rollback update folder creation: C:\Users\$USER\AppData\Local\1Password\update. Error: Os { code: 32, kind: Uncategorized, message: "The process cannot access the file because it is being used by another process." }
ERROR 2024-01-25T19:34:30.554 main(ThreadId(1)) [1P:op-windows-starter\src\installer.rs:183] failed to move app files. Error: Io(PermissionDenied)
INFO 2024-01-25T19:36:43.276 main(ThreadId(1)) [1P:op-windows-starter\src\installer.rs:374] starting C:\Users\$USER\AppData\Local\1Password\app\8\1Password.exe
ERROR 2024-01-25T19:36:43.276 main(ThreadId(1)) [1P:op-windows-starter\src\installer.rs:215] Failed to start previous app. Error: Os { code: 3, kind: NotFound, message: "The system cannot find the path specified." }
ERROR 2024-01-25T19:36:43.276 main(ThreadId(1)) [1P:foundation\op-windows\src\windows\controls\window_class.rs:248] Windows Error Win32(0x00000584): Class still has open windows.

Hello @jorgenpt,

Thanks for your feedback here. I'm happy to hear that the steps to exclude 1Password in MS Defender helped.

For others running in to similar issues with security software installed, you can refer to software developer's support pages for steps to exclude applications from scans. I've also included some more details here to help:
* If you can't install, update, or use 1Password

Have a great day!

I know JetBrains Rider has an option to add things to the Defender exclusion — maybe it would be helpful for the 1Password updater and installed to do the same? This is just the bog standard microsoft defender on windows 11, so it seems likely that this would be affecting a number of people. (Or figure out why Defender is failing — see if there’s a way to wait until it’s done working with the files or something along those lines?)

Hello again @jorgenpt,

This behaviour can also be corrected with anti-virus updates getting the latest signatures. For example, we've seen very brief troubles, in the past after a 1Password update is released. We've recently seen some new updates sent out January 23/24, 2024:
* 1Password Releases

We appreciate the additional feedback here. I'll pass it along!