fix: improve error logging for chat model configuration issues (#458)

* docs: update CHANGELOG for v1.6.0 release

* fix: improve error logging for chat model configuration issues (#358)

- Add detailed error logging in provision.py when model lookup fails
- Add warning logging in models.py when default model is not configured
- Add traceback logging in chat router exception handler
- Update Ollama docs with model name configuration guidance
- Update troubleshooting docs with "Failed to send message" solutions
- Bump version to 1.6.1

* chore: uvlock

CHANGELOG.md

@@ -5,18 +5,33 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [1.6.0] - 2026-01-16
+## [1.6.1] - 2026-01-22
+
+### Fixed
+- "Failed to send message" error with unhelpful logs when chat model is not configured (#358)
+  - Added detailed error logging with model selection context and full traceback
+  - Improved error messages to guide users to Settings → Models
+  - Added warnings when default models are not configured
+
+### Docs
+- Ollama troubleshooting: Added "Model Name Configuration" section emphasizing exact model names from `ollama list`
+- Added troubleshooting entry for "Failed to send message" error with step-by-step solutions
+- Updated AI Chat Issues documentation with model configuration guidance
+
+## [1.6.0] - 2026-01-21
 
 ### Added
 - Content-type aware text chunking with automatic HTML, Markdown, and plain text detection (#350, #142)
 - Unified embedding generation with mean pooling for large content that exceeds model context limits
 - Dedicated embedding commands: `embed_note`, `embed_insight`, `embed_source`
 - New utility modules: `chunking.py` and `embedding.py` in `open_notebook/utils/`
+- Japanese (ja-JP) language support (#450)
 
 ### Changed
 - Embedding is now fire-and-forget: domain models submit embedding commands asynchronously after save
 - `rebuild_embeddings_command` now delegates to individual embed_* commands instead of inline processing
 - Chunk size reduced to 1500 characters for better compatibility with Ollama embedding models
+- Bump Esperanto to 2.16 for increased Ollama context window support
 
 ### Removed
 - Legacy embedding commands: `embed_single_item_command`, `embed_chunk_command`, `vectorize_source_command`
@@ -25,6 +40,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 - Embedding failures when content exceeds model context limits (#350, #142)
+- Empty note titles when saving from chat (clean thinking tags from prompt graph output)
+- Orphaned embedding/insight records when deleting sources (cascade delete)
+- Search results crash with null parent_id (defensive frontend check)
+- Database migration 10 cleans up existing orphaned records
 
 ## [1.5.2] - 2026-01-15
 

api/routers/chat.py

@@ -1,4 +1,5 @@
 import asyncio
+import traceback
 from typing import Any, Dict, List, Optional
 
 from fastapi import APIRouter, HTTPException, Query
@@ -381,7 +382,13 @@ async def execute_chat(request: ExecuteChatRequest):
     except NotFoundError:
         raise HTTPException(status_code=404, detail="Session not found")
     except Exception as e:
-        logger.error(f"Error executing chat: {str(e)}")
+        # Log detailed error with context for debugging
+        logger.error(
+            f"Error executing chat: {str(e)}\n"
+            f"  Session ID: {request.session_id}\n"
+            f"  Model override: {request.model_override}\n"
+            f"  Traceback:\n{traceback.format_exc()}"
+        )
         raise HTTPException(status_code=500, detail=f"Error executing chat: {str(e)}")
 
 

docs/5-CONFIGURATION/ollama.md

@@ -233,6 +233,45 @@ ollama pull qwen3
 
 ## Troubleshooting
 
+### Model Name Configuration (Critical)
+
+**⚠️ IMPORTANT: Model names must exactly match the output of `ollama list`**
+
+This is the most common cause of "Failed to send message" errors. Open Notebook requires the **exact model name** as it appears in Ollama.
+
+**Step 1: Get the exact model name**
+```bash
+ollama list
+```
+
+Example output:
+```
+NAME                        ID              SIZE      MODIFIED
+mxbai-embed-large:latest    468836162de7    669 MB    7 minutes ago
+gemma3:12b                  f4031aab637d    8.1 GB    2 months ago
+qwen3:32b                   030ee887880f    20 GB     9 days ago
+```
+
+**Step 2: Use the exact name when adding the model in Open Notebook**
+
+| ✅ Correct | ❌ Wrong |
+|-----------|----------|
+| `gemma3:12b` | `gemma3` (missing tag) |
+| `qwen3:32b` | `qwen3-32b` (wrong format) |
+| `mxbai-embed-large:latest` | `mxbai-embed-large` (missing tag) |
+
+**Note:** Some models use `:latest` as the default tag. If `ollama list` shows `model:latest`, you must use `model:latest` in Open Notebook, not just `model`.
+
+**Step 3: Configure in Open Notebook**
+
+1. Go to **Settings → Models**
+2. Click **Add Model**
+3. Enter the **exact name** from `ollama list`
+4. Select provider: `ollama`
+5. Select type: `language` (for chat) or `embedding` (for search)
+6. Save the model
+7. Set it as the default for the appropriate task (chat, transformation, etc.)
+
 ### Common Issues
 
 **1. "Ollama unavailable" in Open Notebook**
@@ -324,6 +363,50 @@ OLLAMA_HOST=0.0.0.0:8080 ollama serve
 export OLLAMA_API_BASE=http://localhost:8080
 ```
 
+**6. "Failed to send message" in Chat**
+
+**Symptom:** Chat shows "Failed to send message" toast notification. Logs may show:
+```
+Error executing chat: Model is not a LanguageModel: None
+```
+
+**Causes (in order of likelihood):**
+
+1. **Model name mismatch**: The model name in Open Notebook doesn't exactly match `ollama list`
+2. **No default model configured**: You haven't set a default chat model in Settings → Models
+3. **Model was deleted**: You removed the model from Ollama but didn't update Open Notebook's defaults
+4. **Model record deleted**: The model was removed from Open Notebook but is still set as default
+
+**Solutions:**
+
+**Check 1: Verify model names match exactly**
+```bash
+# Get exact model names from Ollama
+ollama list
+
+# Compare with what's configured in Open Notebook
+# Go to Settings → Models and verify the names match EXACTLY
+```
+
+**Check 2: Verify default models are set**
+1. Go to **Settings → Models**
+2. Scroll to **Default Models** section
+3. Ensure **Default Chat Model** has a value selected
+4. If empty, select an available language model
+
+**Check 3: Refresh after changes**
+If you've added/removed models in Ollama:
+1. Refresh the Open Notebook page
+2. Go to Settings → Models
+3. Re-add any missing models with exact names from `ollama list`
+4. Re-select default models if needed
+
+**Check 4: Test the model directly**
+```bash
+# Verify Ollama can use the model
+ollama run gemma3:12b "Hello, world"
+```
+
 ### Docker-Specific Troubleshooting
 
 **1. Host networking on Linux:**

docs/6-TROUBLESHOOTING/ai-chat-issues.md

@@ -4,6 +4,61 @@ Problems with AI models, chat, and response quality.
 
 ---
 
+## "Failed to send message" Error
+
+**Symptom:** Chat shows "Failed to send message" toast. Logs show:
+```
+Error executing chat: Model is not a LanguageModel: None
+```
+
+**Cause:** No valid language model configured for chat
+
+**Solutions:**
+
+### Solution 1: Check Default Model Configuration
+```
+1. Go to Settings → Models
+2. Scroll to "Default Models" section
+3. Verify "Default Chat Model" has a model selected
+4. If empty, select an available language model
+5. Click Save
+```
+
+### Solution 2: Verify Model Names (Ollama Users)
+```bash
+# Get exact model names
+ollama list
+
+# Example output:
+# NAME                   SIZE      MODIFIED
+# gemma3:12b            8.1 GB    2 months ago
+
+# The model name in Open Notebook must be EXACTLY "gemma3:12b"
+# NOT "gemma3" or "gemma3-12b"
+```
+
+### Solution 3: Re-add Missing Models
+```
+1. Note the exact model names from your provider
+2. Go to Settings → Models
+3. Delete any misconfigured models
+4. Add models with exact names
+5. Set new defaults
+```
+
+### Solution 4: Check Model Still Exists
+```bash
+# For Ollama: verify model is installed
+ollama list
+
+# For cloud providers: verify API key is valid
+# and you have access to the model
+```
+
+> **Tip:** This error often occurs when you delete a model from Ollama but forget to update the default models in Open Notebook. Always re-configure defaults after removing models.
+
+---
+
 ## "Models not available" or "Models not showing"
 
 **Symptom:** Settings → Models shows empty, or "No models configured"

open_notebook/ai/models.py

@@ -187,9 +187,21 @@ class ModelManager:
             model_id = defaults.large_context_model
 
         if not model_id:
+            logger.warning(
+                f"No default model configured for type '{model_type}'. "
+                f"Please go to Settings → Models and set a default model."
+            )
             return None
 
-        return await self.get_model(model_id, **kwargs)
+        try:
+            return await self.get_model(model_id, **kwargs)
+        except ValueError as e:
+            logger.error(
+                f"Failed to load default model for type '{model_type}': {e}. "
+                f"The configured model_id '{model_id}' may have been deleted or misconfigured. "
+                f"Please go to Settings → Models and reconfigure the default model."
+            )
+            return None
 
 
 model_manager = ModelManager()

open_notebook/ai/provision.py

@@ -16,17 +16,45 @@ async def provision_langchain_model(
     Otherwise, returns the default model for the given type
     """
     tokens = token_count(content)
+    model = None
+    selection_reason = ""
 
     if tokens > 105_000:
+        selection_reason = f"large_context (content has {tokens} tokens)"
         logger.debug(
             f"Using large context model because the content has {tokens} tokens"
         )
         model = await model_manager.get_default_model("large_context", **kwargs)
     elif model_id:
+        selection_reason = f"explicit model_id={model_id}"
         model = await model_manager.get_model(model_id, **kwargs)
     else:
+        selection_reason = f"default for type={default_type}"
         model = await model_manager.get_default_model(default_type, **kwargs)
 
     logger.debug(f"Using model: {model}")
-    assert isinstance(model, LanguageModel), f"Model is not a LanguageModel: {model}"
+
+    if model is None:
+        logger.error(
+            f"Model provisioning failed: No model found. "
+            f"Selection reason: {selection_reason}. "
+            f"model_id={model_id}, default_type={default_type}. "
+            f"Please check Settings → Models and ensure a default model is configured for '{default_type}'."
+        )
+        raise ValueError(
+            f"No model configured for {selection_reason}. "
+            f"Please go to Settings → Models and configure a default model for '{default_type}'."
+        )
+
+    if not isinstance(model, LanguageModel):
+        logger.error(
+            f"Model type mismatch: Expected LanguageModel but got {type(model).__name__}. "
+            f"Selection reason: {selection_reason}. "
+            f"model_id={model_id}, default_type={default_type}."
+        )
+        raise ValueError(
+            f"Model is not a LanguageModel: {model}. "
+            f"Please check that the model configured for '{default_type}' is a language model, not an embedding or speech model."
+        )
+
     return model.to_langchain()

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "open-notebook"
-version = "1.6.0"
+version = "1.6.1"
 description = "An open source implementation of a research assistant, inspired by Google Notebook LM"
 authors = [
     {name = "Luis Novo", email = "lfnovo@gmail.com"}

uv.lock

@@ -2376,7 +2376,7 @@ wheels = [
 
 [[package]]
 name = "open-notebook"
-version = "1.6.0"
+version = "1.6.1"
 source = { editable = "." }
 dependencies = [
     { name = "ai-prompter" },