bug: 🐛 failure to decrypt when sending message to user with letter sealing off

[clins1994]

Bug Report: failure to decrypt when sending message to user with letter sealing off

Describe the bug

• LSON - LINE User with Letter Sealed ON
• LSOFF - LINE User with Letter Sealed OFF
• BEEPERD - Beeper Desktop
• BEEPERM - Beeper Mobile
• LINEM - LINE Mobile

ID	Status	Header
1	❌	Message sent via BEEPER from LSON to LSOFF directly
2	❌	Message sent via BEEPER from LSON to group with LSOFF
3	✅	Message sent via LINEM from LSON is displayed fine in BEEPERD & BEEPERM
4	✅	Message sent via LINEM from LSOFF is displayed fine in BEEPERD & BEEPERM
5	✅	Message sent via BEEPER from LSON to other group works
6	✅	Message sent via BEEPER from LSON to other LSON works

To Reproduce

N/A

Expected behavior

N/A

Screenshots or logs

Screenshot from LINEM

Group

Direct

Screenshot from BEEPERM

Group

Direct

Screenshot from BEEPERD

Group

Direct

Logs from bridge

matrix-line-1  | 2026-03-16T02:06:09.67Z DBG Decrypting received event event_id=[EVENT_ID] session_id=[SESSION_ID]
matrix-line-1  | 2026-03-16T02:06:09.67Z DBG Sent response to transaction req_id=82 transaction_id=[TRANSACTION_ID] ws_command=transaction
matrix-line-1  | 2026-03-16T02:06:09.672Z DBG Upserting megolm inbound group session account_id= action="decrypt megolm event" event_id=[EVENT_ID] is_scheduled=false key_backup_version= max_age=2592000000 max_messages=10000 received_at=2026-03-16T02:00:01.239559997Z room_id=[ROOM_ID] sender=[USER_EMAIL] sender_key=[SENDER_KEY] session_id=[SESSION_ID] signing_key=[SIGNING_KEY]
matrix-line-1  | 2026-03-16T02:06:09.673Z DBG Ratchet safety data changed (ratchet state didn't change) action="decrypt megolm event" event_id=[EVENT_ID] lost_indices=[] max_messages=10000 missed_indices=[0,1] new_ratchet_index=0 next_new_index=3 prev_ratchet_index=1 sender=[USER_EMAIL] sender_key=[SENDER_KEY] session_id=[SESSION_ID]
matrix-line-1  | 2026-03-16T02:06:09.673Z DBG Event decrypted successfully action="decrypt megolm event" decrypted_event_type="m.room.message (message)" event_id=[EVENT_ID] message_index=2 sender=[USER_EMAIL] sender_key=[SENDER_KEY] session_id=[SESSION_ID]
matrix-line-1  | 2026-03-16T02:06:09.719Z DBG fetchAndUnwrapGroupKey before encrypt failed error="API error 400: {\"code\":10051,\"message\":\"RESPONSE_ERROR\",\"data\":{\"name\":\"TalkException\",\"message\":\"TalkException\",\"code\":5,\"reason\":\"not found\",\"parameterMap\":null}}" chat_mid=[CHAT_MID]
matrix-line-1  | 2026-03-16T02:06:09.754Z ERR Failed to handle Matrix message error="encrypt failed: no group key found for [CHAT_MID]" action="handle matrix event" event_id=[EVENT_ID] event_loop_index=31 event_type=m.room.message login_id=[LOGIN_ID] portal_id=[PORTAL_ID] portal_mxid=[PORTAL_MXID] sender=[USER_EMAIL]
matrix-line-1  | 2026-03-16T02:06:10.078Z DBG Request completed action="handle matrix event" beeper_request_id=[REQUEST_ID] duration=322.817564 event_id=[EVENT_ID] event_loop_index=31 event_type=m.room.message method=PUT portal_id=[PORTAL_ID] portal_mxid=[PORTAL_MXID] req_body={"internal_error":"encrypt failed: no group key found for [CHAT_MID]","m.relates_to":{"event_id":"[EVENT_ID]","rel_type":"m.reference"},"reason":"m.event_not_handled","status":"FAIL_RETRIABLE"} req_id=158 response_length=73 response_mime=application/json sender=[USER_EMAIL] status_code=200 url=[REDACTED_URL]
matrix-line-1  | 2026-03-16T02:06:40.274Z WRN SSE Disconnected error="context deadline exceeded (Client.Timeout or context cancellation while reading body)"

Additional context

• gist with line chrome extension network logs

[clins1994]

Relates to #42 despite not being auth related

[clins1994]

Sanity check: I logged out and logged back in to the bridge. Same behavior remains

[highesttt]

pull from the 54-bug-failure-to-decrypt-when-sending-message-to-user-with-letter-sealing-off branch and tell me if the issue still occurs

[clins1994]

In case it might help. Here are the successful Beeper bridge logs when LSON and LSOFF exchange a message directly and in group via LINEM. These are displayed normally in BEEPERM and BEEPERD

1. Direct Message - Sent

matrix-line-1  | 2026-03-16T02:47:32.75Z DBG Handling remote event action="handle remote event" bridge_evt_type=RemoteEventMessage event_loop_index=11 msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_DM] portal_mxid=[PORTAL_MXID_DM] remote_message_id=[MESSAGE_ID] remote_sender={"is_from_me":true,"sender_login":"","user_id":"[USER_ID]"} source_id=[USER_ID]
matrix-line-1  | 2026-03-16T02:47:32.752Z DBG Encrypted event successfully action="handle remote event" bridge_evt_type=RemoteEventMessage event_loop_index=11 event_type=m.room.message expected_index=6 message_index=6 msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_DM] portal_mxid=[PORTAL_MXID_DM] remote_message_id=[MESSAGE_ID] remote_sender={"is_from_me":true,"sender_login":"","user_id":"[USER_ID]"} room_id=[ROOM_ID_DM] session_id=[SESSION_ID] source_id=[USER_ID] state_key=null
matrix-line-1  | 2026-03-16T02:47:33.671Z DBG Request completed action="handle remote event" beeper_request_id=[REQUEST_ID] bridge_evt_type=RemoteEventMessage duration=917.443385 event_loop_index=11 method=PUT msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_DM] portal_mxid=[PORTAL_MXID_DM] remote_message_id=[MESSAGE_ID] remote_sender={"is_from_me":true,"sender_login":"","user_id":"[USER_ID]"} req_body={"algorithm":"m.megolm.v1.aes-sha2","ciphertext":"[CIPHERTEXT]","device_id":"[DEVICE_ID]","fi.mau.double_puppet_source":"matrix-line","sender_key":"[SENDER_KEY]","session_id":"[SESSION_ID]"} req_id=649 response_length=73 response_mime=application/json source_id=[USER_ID] status_code=200 url=[REDACTED_URL]
matrix-line-1  | 2026-03-16T02:47:33.671Z DBG Sent message part to Matrix action="handle remote event" bridge_evt_type=RemoteEventMessage event_id=[EVENT_ID] event_loop_index=11 msg_id=[MESSAGE_ID] part_id= portal_id=[PORTAL_ID_DM] portal_mxid=[PORTAL_MXID_DM] remote_message_id=[MESSAGE_ID] remote_sender={"is_from_me":true,"sender_login":"","user_id":"[USER_ID]"} source_id=[USER_ID]

---

2. Direct Message - Received

matrix-line-1  | 2026-03-16T02:47:41.864Z DBG Handling remote event action="handle remote event" bridge_evt_type=RemoteEventReadReceipt event_loop_index=12 portal_id=[PORTAL_ID_DM] portal_mxid=[PORTAL_MXID_DM] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} source_id=[USER_ID]
matrix-line-1  | 2026-03-16T02:47:42.17Z DBG Request completed action="handle remote event" beeper_request_id=[REQUEST_ID] bridge_evt_type=RemoteEventReadReceipt duration=304.424252 event_loop_index=12 method=POST portal_id=[PORTAL_ID_DM] portal_mxid=[PORTAL_MXID_DM] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} req_body={"com.beeper.read.extra":{"ts":1773629259086},"m.read":"[EVENT_ID]"} req_id=650 response_length=3 response_mime=application/json source_id=[USER_ID] status_code=200 url=[REDACTED_URL]
matrix-line-1  | 2026-03-16T02:47:42.17Z DBG Bridged read receipt action="handle remote event" bridge_evt_type=RemoteEventReadReceipt event_loop_index=12 portal_id=[PORTAL_ID_DM] portal_mxid=[PORTAL_MXID_DM] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} source_id=[USER_ID] target_mxid=[EVENT_ID]
matrix-line-1  | 2026-03-16T02:47:42.171Z DBG Handling remote event action="handle remote event" bridge_evt_type=RemoteEventMessage event_loop_index=13 msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_DM] portal_mxid=[PORTAL_MXID_DM] remote_message_id=[MESSAGE_ID] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} source_id=[USER_ID]
matrix-line-1  | 2026-03-16T02:47:42.173Z DBG Encrypted event successfully action="handle remote event" bridge_evt_type=RemoteEventMessage event_loop_index=13 event_type=m.room.message expected_index=7 message_index=7 msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_DM] portal_mxid=[PORTAL_MXID_DM] remote_message_id=[MESSAGE_ID] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} room_id=[ROOM_ID_DM] session_id=[SESSION_ID] source_id=[USER_ID] state_key=null
matrix-line-1  | 2026-03-16T02:47:42.477Z DBG Request completed action="handle remote event" beeper_request_id=[REQUEST_ID] bridge_evt_type=RemoteEventMessage duration=302.993157 event_loop_index=13 method=PUT msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_DM] portal_mxid=[PORTAL_MXID_DM] remote_message_id=[MESSAGE_ID] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} req_body={"algorithm":"m.megolm.v1.aes-sha2","ciphertext":"[CIPHERTEXT]","device_id":"[DEVICE_ID]","sender_key":"[SENDER_KEY]","session_id":"[SESSION_ID]"} req_id=651 response_length=73 response_mime=application/json source_id=[USER_ID] status_code=200 url=[REDACTED_URL]
matrix-line-1  | 2026-03-16T02:47:42.477Z DBG Sent message part to Matrix action="handle remote event" bridge_evt_type=RemoteEventMessage event_id=[EVENT_ID] event_loop_index=13 msg_id=[MESSAGE_ID] part_id= portal_id=[PORTAL_ID_DM] portal_mxid=[PORTAL_MXID_DM] remote_message_id=[MESSAGE_ID] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} source_id=[USER_ID]

---

3. Group - Sent

matrix-line-1  | 2026-03-16T02:48:05.519Z DBG Handling remote event action="handle remote event" bridge_evt_type=RemoteEventMessage event_loop_index=24 msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_GROUP] portal_mxid=[PORTAL_MXID_GROUP] remote_message_id=[MESSAGE_ID] remote_sender={"is_from_me":true,"sender_login":"","user_id":"[USER_ID]"} source_id=[USER_ID]
matrix-line-1  | 2026-03-16T02:48:05.521Z DBG Encrypted event successfully action="handle remote event" bridge_evt_type=RemoteEventMessage event_loop_index=24 event_type=m.room.message expected_index=16 message_index=16 msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_GROUP] portal_mxid=[PORTAL_MXID_GROUP] remote_message_id=[MESSAGE_ID] remote_sender={"is_from_me":true,"sender_login":"","user_id":"[USER_ID]"} room_id=[ROOM_ID_GROUP] session_id=[SESSION_ID_GROUP] source_id=[USER_ID] state_key=null
matrix-line-1  | 2026-03-16T02:48:05.824Z DBG Request completed action="handle remote event" beeper_request_id=[REQUEST_ID] bridge_evt_type=RemoteEventMessage duration=301.85751 event_loop_index=24 method=PUT msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_GROUP] portal_mxid=[PORTAL_MXID_GROUP] remote_message_id=[MESSAGE_ID] remote_sender={"is_from_me":true,"sender_login":"","user_id":"[USER_ID]"} req_body={"algorithm":"m.megolm.v1.aes-sha2","ciphertext":"[CIPHERTEXT]","device_id":"[DEVICE_ID]","fi.mau.double_puppet_source":"matrix-line","sender_key":"[SENDER_KEY]","session_id":"[SESSION_ID_GROUP]"} req_id=652 response_length=73 response_mime=application/json source_id=[USER_ID] status_code=200 url=[REDACTED_URL]
matrix-line-1  | 2026-03-16T02:48:05.824Z DBG Sent message part to Matrix action="handle remote event" bridge_evt_type=RemoteEventMessage event_id=[EVENT_ID] event_loop_index=24 msg_id=[MESSAGE_ID] part_id= portal_id=[PORTAL_ID_GROUP] portal_mxid=[PORTAL_MXID_GROUP] remote_message_id=[MESSAGE_ID] remote_sender={"is_from_me":true,"sender_login":"","user_id":"[USER_ID]"} source_id=[USER_ID]

---

4. Group - Received

matrix-line-1  | 2026-03-16T02:48:10.224Z DBG Handling remote event action="handle remote event" bridge_evt_type=RemoteEventReadReceipt event_loop_index=25 portal_id=[PORTAL_ID_GROUP] portal_mxid=[PORTAL_MXID_GROUP] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} source_id=[USER_ID]
matrix-line-1  | 2026-03-16T02:48:10.53Z DBG Request completed action="handle remote event" beeper_request_id=[REQUEST_ID] bridge_evt_type=RemoteEventReadReceipt duration=305.354002 event_loop_index=25 method=POST portal_id=[PORTAL_ID_GROUP] portal_mxid=[PORTAL_MXID_GROUP] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} req_body={"com.beeper.read.extra":{"ts":1773629290180},"m.read":"[EVENT_ID]"} req_id=653 response_length=3 response_mime=application/json source_id=[USER_ID] status_code=200 url=[REDACTED_URL]
matrix-line-1  | 2026-03-16T02:48:10.531Z DBG Bridged read receipt action="handle remote event" bridge_evt_type=RemoteEventReadReceipt event_loop_index=25 portal_id=[PORTAL_ID_GROUP] portal_mxid=[PORTAL_MXID_GROUP] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} source_id=[USER_ID] target_mxid=[EVENT_ID]
matrix-line-1  | 2026-03-16T02:48:14.749Z DBG Handling remote event action="handle remote event" bridge_evt_type=RemoteEventMessage event_loop_index=26 msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_GROUP] portal_mxid=[PORTAL_MXID_GROUP] remote_message_id=[MESSAGE_ID] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} source_id=[USER_ID]
matrix-line-1  | 2026-03-16T02:48:14.751Z DBG Encrypted event successfully action="handle remote event" bridge_evt_type=RemoteEventMessage event_loop_index=26 event_type=m.room.message expected_index=17 message_index=17 msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_GROUP] portal_mxid=[PORTAL_MXID_GROUP] remote_message_id=[MESSAGE_ID] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} room_id=[ROOM_ID_GROUP] session_id=[SESSION_ID_GROUP] source_id=[USER_ID] state_key=null
matrix-line-1  | 2026-03-16T02:48:15.041Z DBG Request completed action="handle remote event" beeper_request_id=[REQUEST_ID] bridge_evt_type=RemoteEventMessage duration=289.245075 event_loop_index=26 method=PUT msg_id=[MESSAGE_ID] portal_id=[PORTAL_ID_GROUP] portal_mxid=[PORTAL_MXID_GROUP] remote_message_id=[MESSAGE_ID] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} req_body={"algorithm":"m.megolm.v1.aes-sha2","ciphertext":"[CIPHERTEXT]","device_id":"[DEVICE_ID]","sender_key":"[SENDER_KEY]","session_id":"[SESSION_ID_GROUP]"} req_id=654 response_length=73 response_mime=application/json source_id=[USER_ID] status_code=200 url=[REDACTED_URL]
matrix-line-1  | 2026-03-16T02:48:15.041Z DBG Sent message part to Matrix action="handle remote event" bridge_evt_type=RemoteEventMessage event_id=[EVENT_ID] event_loop_index=26 msg_id=[MESSAGE_ID] part_id= portal_id=[PORTAL_ID_GROUP] portal_mxid=[PORTAL_MXID_GROUP] remote_message_id=[MESSAGE_ID] remote_sender={"sender_login":"","user_id":"[REMOTE_USER_ID]"} source_id=[USER_ID]

[highesttt]

Did you try with the new fixes?

[clins1994]

@highesttt just a second few minutes. rebuilding. takes a while

[clins1994]

@highesttt now nothing works with "not logged in" 😢 logs from sending a message

I simply pulled latest and ran docker compose up --build -d

matrix-line-1  | 2026-03-16T03:07:08.308Z DBG Pinging appservice websocket
matrix-line-1  | 2026-03-16T03:07:08.639Z DBG Websocket ping returned success duration=330.831985 req_duration=172.74553 resp_duration=158.086441
matrix-line-1  | 2026-03-16T03:07:48.992Z DBG Starting handling of transaction content={"edu":1,"pdu":0} req_id=60 transaction_id=[TRANSACTION_ID] ws_command=transaction
matrix-line-1  | 2026-03-16T03:07:48.992Z DBG Finished dispatching events from transaction req_id=60 transaction_id=[TRANSACTION_ID] ws_command=transaction
matrix-line-1  | 2026-03-16T03:07:48.992Z DBG Sent response to transaction req_id=60 transaction_id=[TRANSACTION_ID] ws_command=transaction
matrix-line-1  | 2026-03-16T03:07:49.299Z DBG Starting handling of transaction content={"edu":1,"pdu":0} req_id=61 transaction_id=[TRANSACTION_ID] ws_command=transaction
matrix-line-1  | 2026-03-16T03:07:49.299Z DBG Finished dispatching events from transaction req_id=61 transaction_id=[TRANSACTION_ID] ws_command=transaction
matrix-line-1  | 2026-03-16T03:07:49.3Z DBG Sent response to transaction req_id=61 transaction_id=[TRANSACTION_ID] ws_command=transaction
matrix-line-1  | 2026-03-16T03:07:49.606Z DBG Starting handling of transaction content={"pdu":1} req_id=62 transaction_id=[TRANSACTION_ID] ws_command=transaction
matrix-line-1  | 2026-03-16T03:07:49.606Z DBG Finished dispatching events from transaction req_id=62 transaction_id=[TRANSACTION_ID] ws_command=transaction
matrix-line-1  | 2026-03-16T03:07:49.606Z DBG Decrypting received event event_id=[EVENT_ID] session_id=[SESSION_ID]
matrix-line-1  | 2026-03-16T03:07:49.607Z DBG Sent response to transaction req_id=62 transaction_id=[TRANSACTION_ID] ws_command=transaction
matrix-line-1  | 2026-03-16T03:07:49.609Z DBG Upserting megolm inbound group session account_id= action="decrypt megolm event" event_id=[EVENT_ID] is_scheduled=false key_backup_version= max_age=2592000000 max_messages=10000 received_at=2026-03-16T03:04:31.460877526Z room_id=[ROOM_ID] sender=[USER_EMAIL] sender_key=[SENDER_KEY] session_id=[SESSION_ID] signing_key=[SIGNING_KEY]
matrix-line-1  | 2026-03-16T03:07:49.609Z DBG Ratchet safety data changed (ratchet state didn't change) action="decrypt megolm event" event_id=[EVENT_ID] lost_indices=[] max_messages=10000 missed_indices=[0] new_ratchet_index=0 next_new_index=2 prev_ratchet_index=1 sender=[USER_EMAIL] sender_key=[SENDER_KEY] session_id=[SESSION_ID]
matrix-line-1  | 2026-03-16T03:07:49.61Z DBG Event decrypted successfully action="decrypt megolm event" decrypted_event_type="m.room.message (message)" event_id=[EVENT_ID] message_index=1 sender=[USER_EMAIL] sender_key=[SENDER_KEY] session_id=[SESSION_ID]
matrix-line-1  | 2026-03-16T03:07:49.61Z ERR Failed to get user login to handle Matrix event error="not logged in" action="handle matrix event" event_id=[EVENT_ID] event_loop_index=16 event_type=m.room.message portal_id=[PORTAL_ID] portal_mxid=[PORTAL_MXID] sender=[USER_EMAIL]
matrix-line-1  | 2026-03-16T03:07:50.528Z DBG Request completed action="handle matrix event" beeper_request_id=[REQUEST_ID] duration=916.109828 event_id=[EVENT_ID] event_loop_index=16 event_type=m.room.message method=PUT portal_id=[PORTAL_ID] portal_mxid=[PORTAL_MXID] req_body={"internal_error":"not logged in","m.relates_to":{"event_id":"[EVENT_ID]","rel_type":"m.reference"},"message":"You're not logged in","reason":"m.event_not_handled","status":"FAIL_RETRIABLE"} req_id=498 response_length=73 response_mime=application/json sender=[USER_EMAIL] status_code=200 url=[REDACTED_URL]

Can no longer send messages even on chats that both users are LSON

[highesttt]

does it work with those with letter sealing on?

[highesttt]

What's weird is that the error you have here isn't related to any of the changes i've made 😅

[clins1994]

does it work with those with letter sealing on?
It didn't

I know, right? 😅 💦

I checked out to 324f317c353633d784dd69324751ee7d9ca247bd and rebuilt, its back to normal. LSON <=> LSON chats working. Can't LSON => LSOFF.

Pulling latest and trying again ...

[highesttt]

I've added an extra security check in the latest commit, but it's not needed

The error you have here is because you were logged out from the bridge (because you logged into desktop) before the fix from #53. So, you'll need to re-login again