[Bug] Nextcloud E2EE “key checksums failed” on iOS

[50LUD4]

Since iOs app update 33.0.5.4 (Nextcloud server 33.0.2 self hosted on Cloudron 9.16), I’ve this error:

"End-to-end encryption error, key checksums failed"

I did all kind of test, ending to delete all whole instance and reinstall again. Generating new passphrase, reuploading files... nothing to do.

Encrypted folder is firstly created on MacOS. When opening in iOS, give below error.

Screenshot:

Video:

Video.mp4

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Steps to reproduce

1. Create an empty folder and encrypt on MacOS
2. Put files and folders inside the encrypted folder
3. Open the same folder on iOs

Expected behaviour

Before 33.0.5.4 I could access all encrypted folders on iOS

Actual behaviour

Now, I get error "End-to-end encryption error, key checksums failed"

Logs

https://pastebin.com/V7YXbc3C

Environment data

iOS version: iOS 26.3.1 (a)

Nextcloud iOS app version: 33.0.5.4

Nextcloud MacOS app version: 33.0.2

Server operating system: Ubuntu 24.04.4 LTS Linux 6.8.0-110-generic

Nextcloud version: 33.0.2

[marinofaggiana]

@50LUD4 Thanks for your report, which desktop client version and End-to-end Encryption server app you use ?

[50LUD4]

Hi @marinofaggiana thanks for your feedback.

I’m using 33.0.2 Mac version.

[eroth]

Same issue here. Nextcloud 33.0.2 (self-hosted), E2EE app 2.1.0, iOS app 33.0.6, Nextcloud Desktop Client 33.0.2. Keys were created on April 2nd with an earlier iOS version and worked fine until 33.0.5 dropped on April 17th.

Symptoms:

• "key checksums failed" on iOS when opening encrypted folders
• Desktop client (macOS 33.0.2) works fine with the same mnemonic and can access all encrypted files
• Mnemonic restore on iOS fails with the same error
• Deleting and reinstalling the iOS app does not fix it

The private key stored on the server is in the format encryptedKey|nonce|salt (v1 format). I'm wondering if PRs #4050 and #4052 (merged April 17th) strengthened checksum validation in a way that rejects keys stored in the older format, even when the mnemonic is correct. The desktop client appears to still accept the old format, which is why it works there but not on iOS.

[marinofaggiana]

Thanks for the report, we have already notified the desktop team

[eroth]

Thanks for the report, we have already notified the desktop team

Are you saying it's not an iOS issue and it's related to the desktop app?

[50LUD4]

Hi @marinofaggiana thanks for your efforts.

Given that Nextcloud's E2EE feature is currently broken on iOS, is there a workaround until the issue is fixed?

I tried to create and encrypt folder from iOs, but then folder is not readable on MacOS...

As new Nextcloud user, any suggestion would be useful.

Thanks

[eroth]

Thanks for the report, we have already notified the desktop team

Is there an issue for this for the desktop team we could follow?

[seth-hoisington]

I’m seeing what looks like the same iOS E2EE bug, with some extra detail from a fresh setup:

• Server: Nextcloud 33.0.2 (Docker, Apache image)
• E2EE app: 2.1.0
• Architecture: ARM (server)
• Clients:
  • Desktop: macOS + desktop client 33.0.3 (E2EE works fine here)
  • Mobile: iOS (iOS app v33.0.7.5, E2EE successfully enabled for the same account)

What works:

• I can enable E2EE on either desktop client or iOS client and create an encrypted folder.
• Files inside that folder work flawlessly on the desktop client.
• Server logs only show harmless preview errors (missing thumbnails in appdata_…/preview), no errors about missing keys or unreadable data.
• Files added to encrypted folder using the iOS app work and remain readable until I manipulate it using another device

What fails on iOS:

• If I copy/move/upload files and subfolders into the encrypted folder from the desktop client or web UI, then open that encrypted folder in iOS, I get:
  • “E2EE error, no checksums found”.
  • The iOS app kicks me back out of the encrypted folder/file.
• The same files/folders continue to work correctly on desktop.

Additional notes:

• This happens consistently with E2EE folders that were manipulated (copy/move/upload) from desktop or web after being created.
• The encrypted folder itself remains usable on desktop, so it doesn’t look like server‑side corruption; it appears to be an iOS E2EE metadata / checksum handling problem.
• Tried restarting everything, resetting and reinstalling iOS app, reenabling E2EE, file scans, you name it.

Thank you!

[eroth]

• it appears to be an iOS E2EE metadata / checksum handling problem.

Agree, it would be great to hear from a Nextcloud iOS dev why they feel it's related to Nextcloud Desktop (@marinofaggiana?)

[bcutter]

Same discovered today on latest iOS version v33.0.7 when trying to access certain E2EE subfolders:

Also the desktop clients have been upgraded in the last days.

So @marinofaggiana what broke this and when can we finally return using E2EE on iOS?

I really hope this is not another typical "E2EE is broken, nobody cares to fix for several weeks" situation like we experienced multiple times already in the past.

• Where is the desktop client issue?
• What's the progress?

Be transparent please, thank you.

[marinofaggiana]

We've seen some discrepancies between the desktop version, mobile and the latest server version. A fix will be available soon. We'll soon begin developing a common library for all environments to eliminate these potential discrepancies between different systems.

We apologize for the inconvenience.