Unable to decrypt: The sender's device has not sent us the keys for this message.

[laicon188]

Hello.
In a new version of Riot.im when i send message, another user recieve "Unable to decrypt: The sender's device has not sent us the keys for this message.".
Another user use Android with riot.im or Riot.Desktop, he recieve the same text.
How in Riot.im iOS verify devices in chat.

[jacotec]

What's the status of this? That issue destroys the user acceptance in encrypted rooms rapidly!

Any thoughts from the dev team @manuroe ?

[jacotec]

Anyone? @manuroe
This is a real showstopper and happens every few days here on IOS devices!

[laicon188]

Hello, @jacotec

Update to Element and try to verify users in the chat.
Go to Settings->security and check "never send messages to untrusted sessions" is it on or off?

[jacotec]

Hi @laicon188

We're running the latest Element app on all iDevices. The "Never send messages to untrusted sessions" is off on all devices. All devices of the users are verified, it's happening in 1:1 chats where users always use the same devices (Mostly the iPhone).

It's more a problem that it seems the encryption keys are changing periodically and the key does not seem to be fetched from the server correctly (I have no clue how the key exchange work in detail). We're in the same chat, and suddenly after I write a new message after an hour my wife gets the error message from the thread subject. The only solution is to open Element on the iPad then and request the key from another device. Very bad if you're on the road with just the iPhone.

Seems to be worse since the change from Riot to Element ... but with this step many things got worse like the 3-5 seconds you always need to wait after going into the app to see new messages :(

As the app does not sync in background anymore maybe some new keys pushed by the server are also lost ...

[laicon188]

@jacotec

Are you use your own matrix-synapse server?

[dos1701]

I actually have the same problem.

@laicon188 I do run my own matrix-synapse server:
{"server_version":"1.19.2","python_version":"3.6.9"}

The issue happens only on iOS devices, for example we have a room with 3 iOS devices and just one Android.
The Android one has no issue at all reading all the messages

[jacotec]

Oops, I missed @laicon188 's question ... yes, own servers (but up to date) 😉

[jtrees]

Someone I know frequently encounters this issue. She and all her contacts are on matrix.org.

[igbjnI05bF]

This happens very regularly to everybody that uses a Macintosh telephone on my homeserver. See attachments.

Everybody is verified with each other and all devices are verified. I never have problems on element-android nor element-web

[jacotec]

This is exactly what always happens! The IOS app is, especially since the Element rebranding, a complete pratfall. And the reason that I need to leave Matrix after nearly 3 years, switching over to Rocket Chat. The complete core family is 100% IOS devices and nobody wants to use Element anymore, me included. Now we enjoy ultrafast syncing of new messages after opening the app, no unreadable messages, link previews (promised since years), voice messages (on the roadmap since years...) and so on.

Either I keep Android and IOS apps on the same level, or I just declare "Use it with Android, leave it with IOS".

I still have no clue why they did not start with a common code base (like React-Native) when they started the Riot-X app from scratch. So much love went into the android app, IOS seems to be the unloved stepdaughter.

It's a shame ... Matrix/Element had so much potential ...

[vmario89]

Hi. We have the same issues from time to time between usual Android phones and element running in web browser or desktop. Did not figure out any special scenario which could be dependent on the platform. No idea how to recover those messages. Seem to be lost forever. Happens ~ once or twice per week

[michel-slm]

This started happening on a family member's iPhone (I'm using the Linux desktop client and Android), and... they are not impressed. Both accounts are on matrix.org.

Is there any hypothesis as to what's happening here?

[leesalminen]

Just wanted to chime in that one user on our family homeserver is experiencing the same issue with Element for iOS.

I'm running my own matrix-synapse homeserver (v1.29.0) on Ubuntu 20.04. We have ~10 users.

There's a "full family" Room with all users in it. Whenever I post pictures/videos in that Room from one of my iOS devices (iPhone), one user receives the "unable to decrypt" message.

When I post with Element for Linux, or Element for macOS, this user does not receive the error.

No other reports of this happening.

Just my 2c!

[jtrees]

Can confirm that whenever I see this issue it's in a group from someone on iOS (most of us are on Android or Web). We're all on matrix.org though.

[jakecoppinger]

I have this issue on Android/Desktop sometimes, this resolves the issue in my case:

• Open the chat on your working device
• Open the chat on your problematic device (showing the Unable to decrypt errors)
• Wait around 30 seconds

I've found it then sends the keys across.

I can't guarantee this will help in your case though, hopefully someone from the dev team can look into this further.

[florian6973]

I'm quite annoyed because different people around me experienced this error in iOS and Android many times and it seems to be at random... Is there a way to fix it definetely?

[gradinaruvasile]

It started happening on my server. Since i added a IOS device (we had only Android and Linux before), in one room one user does not receive the messages of the devices (IOA and Android) added since i added the IOS device. Everything is "green" just that this specific user does not receive the messages from the recent devices in this specific room. This user has only 1 device (Element Linux).

Edit: I finally solved this. Turns out that the new devices will be fully validated by all others if the user that has a new device checks on all of his devices' Element app (as in opening it and looking around a bit). The 2 users that had new devices each had another device that was not connected to network when the new devices were created. One of them even had the validation popup appearing when the old device was connected to the network (despite having validated the new device on another one before).

Anyway, after starting the older clients on the other devices, everything works now. It is not ios related because there were Linux, Android and IOS devices involved.

[chn42]

Just stumbled upon this. First thing I've found is, in a room where I can't see one other person, this specific person gets this message, in all other rooms, where I can see this person as participant, the person can decrypt my messages. Probably this happens because my client then doesn't encrypt with the key for this person and therefor it can't be decrypted.

[shmerl]

Is there some workaround for this? It's happening with matrix.org between ios client and a web element (the error is on ios side).

[richvdh]

There are a lot of potential causes for this message. We are tracking them at element-hq/element-meta#245.