When chat history reconstruction produces tool_result messages without a matching tool_use (e.g. partial history, retries, edited chains), strict providers like Anthropic/Vertex reject the payload with HTTP 400
Instead of dropping orphan tool messages (losing context), we now rewire them by injecting a synthetic tool_call into the preceding assistant message so the sequence stays valid
Applies at both the output→message conversion layer (convert_output_to_messages) and the final message sanitization pass (rewire_orphan_tool_messages)
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## 📋 Pull Request Information
**Original PR:** https://github.com/open-webui/open-webui/pull/23013
**Author:** [@Classic298](https://github.com/Classic298)
**Created:** 3/25/2026
**Status:** ❌ Closed
**Base:** `dev` ← **Head:** `tool-call`
---
### 📝 Commits (6)
- [`11c56f0`](https://github.com/open-webui/open-webui/commit/11c56f05fc968f5bf30ac34a6d2857b174ddfbb7) fix: orphaned tool msg
- [`7ae05b5`](https://github.com/open-webui/open-webui/commit/7ae05b5b03c314008d22fe34d42d5c8c0ae8c8af) fix: rewire orphan tool messages instead of dropping them
- [`1b507ae`](https://github.com/open-webui/open-webui/commit/1b507aed0528c85f57b4e8b6a0ce46cd0c4e7801) fix: rewire orphan tool messages with real tool names
- [`0650ebc`](https://github.com/open-webui/open-webui/commit/0650ebcd480c1ba32d182df6a7d3f6573bf83782) fix: log and handle streaming provider error responses
- [`36f2b5b`](https://github.com/open-webui/open-webui/commit/36f2b5bde4c9ca07fe42b88d4c6b9142aa1e09c9) fix: surface provider errors that were silently swallowed
- [`4c1ac90`](https://github.com/open-webui/open-webui/commit/4c1ac90b0f8dc116224ea1ed910e97037c5b12e4) fix: log provider errors from response body (non-exception path)
### 📊 Changes
**4 files changed** (+167 additions, -9 deletions)
<details>
<summary>View changed files</summary>
📝 `backend/open_webui/main.py` (+2 -2)
📝 `backend/open_webui/routers/openai.py` (+10 -0)
📝 `backend/open_webui/utils/middleware.py` (+23 -3)
📝 `backend/open_webui/utils/misc.py` (+132 -4)
</details>
### 📄 Description
## Summary
- When chat history reconstruction produces `tool_result` messages without a matching `tool_use` (e.g. partial history, retries, edited chains), strict providers like Anthropic/Vertex reject the payload with HTTP 400
- Instead of dropping orphan tool messages (losing context), we now **rewire** them by injecting a synthetic `tool_call` into the preceding assistant message so the sequence stays valid
- Applies at both the output→message conversion layer (`convert_output_to_messages`) and the final message sanitization pass (`rewire_orphan_tool_messages`)
### Contributor License Agreement
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> [!NOTE]
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---
<sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>
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📋 Pull Request Information
Original PR: https://github.com/open-webui/open-webui/pull/23013
Author: @Classic298
Created: 3/25/2026
Status: ❌ Closed
Base:
dev← Head:tool-call📝 Commits (6)
11c56f0fix: orphaned tool msg7ae05b5fix: rewire orphan tool messages instead of dropping them1b507aefix: rewire orphan tool messages with real tool names0650ebcfix: log and handle streaming provider error responses36f2b5bfix: surface provider errors that were silently swallowed4c1ac90fix: log provider errors from response body (non-exception path)📊 Changes
4 files changed (+167 additions, -9 deletions)
View changed files
📝
backend/open_webui/main.py(+2 -2)📝
backend/open_webui/routers/openai.py(+10 -0)📝
backend/open_webui/utils/middleware.py(+23 -3)📝
backend/open_webui/utils/misc.py(+132 -4)📄 Description
Summary
tool_resultmessages without a matchingtool_use(e.g. partial history, retries, edited chains), strict providers like Anthropic/Vertex reject the payload with HTTP 400tool_callinto the preceding assistant message so the sequence stays validconvert_output_to_messages) and the final message sanitization pass (rewire_orphan_tool_messages)Contributor License Agreement
🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.