Bug type

Behavior bug (incorrect output/state without crash)

Beta release blocker

No

Summary

Seen in main webchat: "Error: reply session initialization conflicted for agent:main:main"

Steps to reproduce

1. Open the main webchat
2. Take a couple simple turns in chat - tool calls or not seems not to matter. The number of turns can vary. I've seen it mostly happen after one turn, though in testing before creating this issue, it happened with two. Another possible factor: I can get it to reliably happen when the model is in non-thinking mode, but when I enable thinking/reasoning, I don't recall seeing it happen at all. The model I use, when in non-thinking mode, replies more quickly, often in under a second.
3. After a turn or two, "Error: reply session initialization conflicted for agent:main:main" appears in the UI and there are corresponding log messages - copies provided below. At that point it's not possible to continue the session; it's broken at that point short of restarting the gateway. (Only if I restart the gateway can I continue.) New sessions also under main work fine.

Expected behavior

Main webchat sessions should proceed normally, as usual.

Actual behavior

Seen in main webchat: "Error: reply session initialization conflicted for agent:main:main" Attempts to take another turn are repeatedly met with this message. The main webchat is broken at that point. /reset is met with the same message.

OpenClaw version

2026.6.11

Operating system

Ubuntu 24.04

Install method

npm global

Model

Qwen3.6-35B-A3B

Provider / routing chain

openclaw -> llama.cpp API -> model

Additional provider/model setup details

No response

Logs

12:34:00-04:00 error diagnostic {"subsystem":"diagnostic"} message dispatch completed: channel=webchat sessionId=unknown sessionKey=agent:main:main source=replyResolver outcome=error duration=38ms error="Error: reply session initialization conflicted for agent:main:main"
12:34:00-04:00 error diagnostic {"subsystem":"diagnostic"} message processed: channel=webchat chatId=unknown messageId=1ca3bfc5-367a-4502-a3d4-f88bbaa216b8 sessionId=abe3128d-dc17-455d-b9b8-9af128b13c53 sessionKey=agent:main:main outcome=error duration=58ms error="Error: reply session initialization conflicted for agent:main:main"

Screenshots, recordings, and evidence

No response

Impact and severity

Blocks workflow until gateway restarted (top-level main session is defunct at that point).
Frequency: always but can take variable number of turns before it happens.

Additional information

This also happens in 2026.6.11-beta.1 and -beta.2.