Requesting mnemonic from time to time

[oleua]

I've found that each time the desktop client update or the upgrade of the server I have to enter the mnemonic, as the E2E becomes disabled. Consequently, the desktop client re-syncs all the encrypted files. In my opinion, this is resource consuming and excessive operation.

UPD Moreover, it happens from time to time event without upgrading!

Is that possible to ommit it?

[ACandian]

Hi,

I just encountered a similar issue recently. This never happened before (I've been using E2EE for almost 2 years now), but now it did twice in a couple of months.

I had 2 similar and yet slightly different issues :

• First time, the mnemonic was forgotten on every clients at once (3 computers and 3 mobile phones) on 1 account.
• Second time, only my main computer (so far) forgot the mnemonic, but on 2 separate accounts from 2 different servers.

Right now, I couldn't find anything useful in the client logs, but I'm still looking.

Edit 20th of November 2025: It happened again today, the client lost the mnemonic for both of my accounts.

[ACandian]

I finally found a warning in the logs :

clientsideencryption.cpp:1408 :	Client certificate is invalid. Could not check it against the server public key
clientsideencryption.cpp:2394 :	Error invalid server public key

After looking into the code, it seems to be a wanted behaviour, updated recently https://github.com/nextcloud/desktop/blame/c0ca58392e19262d71a749bf27270e205e02d8ab/src/libsync/clientsideencryption.cpp#L2394 .

I'm not yet sure what the check actually do to trigger the cleaning, but at the very least, it would be nice to have some kind of warning for users instead of them just discovering that their data are gone without any explanation.