I have searched for any existing and/or related issues.
I have searched for any existing and/or related discussions.
I have also searched in the CLOSED issues AND CLOSED discussions and found no related items (your issue might already be addressed on the development branch!).
I am using the latest version of Open WebUI.
Installation Method
Docker
Open WebUI Version
v0.8.9
Ollama Version (if applicable)
v0.17.4
Operating System
Alpine 3.23
Browser (if applicable)
Firefox
Confirmation
I have read and followed all instructions in README.md.
I am using the latest version of both Open WebUI and Ollama.
I have included the browser console logs.
I have included the Docker container logs.
I have provided every relevant configuration, setting, and environment variable used in my setup.
I have clearly listed every relevant configuration, custom setting, environment variable, and command-line option that influences my setup (such as Docker Compose overrides, .env values, browser settings, authentication configurations, etc).
I have documented step-by-step reproduction instructions that are precise, sequential, and leave nothing to interpretation. My steps:
Start with the initial platform/version/OS and dependencies used,
Specify exact install/launch/configure commands,
List URLs visited, user input (incl. example values/emails/passwords if needed),
Describe all options and toggles enabled or changed,
Include any files or environmental changes,
Identify the expected and actual result at each stage,
Ensure any reasonably skilled user can follow and hit the same issue.
Expected Behavior
When I have enabled fallbacks and specified a default fallback model, the fallback gets used when the current base model of my custom model is unavailable.
Actual Behavior
When I have enabled fallbacks and specified a default fallback model, I get a 404: Model not found error when the current base model of my custom model is unavailable.
Steps to Reproduce
Set up two ollama instances, e.g. ollama-a and ollama-b
Create a custom model that uses a base model from ollama-a, e.g. ollama-a/gpt-oss:20b
Set the default model to a model from ollama-b, e.g. ollama-b/ministral-3:3b
Chat with the custom model and observe it is using ollama-a/gpt-oss:20b correctly.
Take down ollama-a instance.
Chat with custom model and observe the error
Logs & Screenshots
open_webui.main:process_chat:1889 - Error processing chat payload: 404: Model not found
Additional Information
This is happening because model_info_params.get("base_model_id") seems to be missing in all situations (instance down or not), so this entire block gets skipped:
As a consequence, model and form_data['model'] stay as their current values and not the fallback model, which fails downstream in the pipeline. I also experimented with forcing that block to run by manipulating the code directly on my deployment, and it does proceed to processing the chat, but fails somewhere else downstream more silently -- perhaps for reasons related to the original problem described here happening elsewhere.
Originally created by @castielwaverly on GitHub (Mar 8, 2026).
Original GitHub issue: https://github.com/open-webui/open-webui/issues/22456
### Check Existing Issues
- [x] I have searched for any existing and/or related issues.
- [x] I have searched for any existing and/or related discussions.
- [x] I have also searched in the CLOSED issues AND CLOSED discussions and found no related items (your issue might already be addressed on the development branch!).
- [x] I am using the latest version of Open WebUI.
### Installation Method
Docker
### Open WebUI Version
v0.8.9
### Ollama Version (if applicable)
v0.17.4
### Operating System
Alpine 3.23
### Browser (if applicable)
Firefox
### Confirmation
- [x] I have read and followed all instructions in `README.md`.
- [x] I am using the latest version of **both** Open WebUI and Ollama.
- [x] I have included the browser console logs.
- [x] I have included the Docker container logs.
- [x] I have **provided every relevant configuration, setting, and environment variable used in my setup.**
- [x] I have clearly **listed every relevant configuration, custom setting, environment variable, and command-line option that influences my setup** (such as Docker Compose overrides, .env values, browser settings, authentication configurations, etc).
- [x] I have documented **step-by-step reproduction instructions that are precise, sequential, and leave nothing to interpretation**. My steps:
- Start with the initial platform/version/OS and dependencies used,
- Specify exact install/launch/configure commands,
- List URLs visited, user input (incl. example values/emails/passwords if needed),
- Describe all options and toggles enabled or changed,
- Include any files or environmental changes,
- Identify the expected and actual result at each stage,
- Ensure any reasonably skilled user can follow and hit the same issue.
### Expected Behavior
When I have enabled fallbacks and specified a default fallback model, the fallback gets used when the current base model of my custom model is unavailable.
### Actual Behavior
When I have enabled fallbacks and specified a default fallback model, I get a `404: Model not found` error when the current base model of my custom model is unavailable.
### Steps to Reproduce
1. Set up two ollama instances, e.g. `ollama-a` and `ollama-b`
2. Create a custom model that uses a base model from `ollama-a`, e.g. `ollama-a/gpt-oss:20b`
3. Set the default model to a model from `ollama-b`, e.g. `ollama-b/ministral-3:3b`
4. Chat with the custom model and observe it is using `ollama-a/gpt-oss:20b` correctly.
5. Take down `ollama-a` instance.
6. Chat with custom model and observe the error
### Logs & Screenshots
```
open_webui.main:process_chat:1889 - Error processing chat payload: 404: Model not found
```
### Additional Information
This is happening because `model_info_params.get("base_model_id")` seems to be missing in all situations (instance down or not), so this entire block gets skipped:
https://github.com/open-webui/open-webui/blob/6c159a97b7efdfdbfa262ebd26823a2d695b561d/backend/open_webui/main.py#L1734-L1741
This model info comes from the global config as the base, with specifics overwritten by the model params
https://github.com/open-webui/open-webui/blob/6c159a97b7efdfdbfa262ebd26823a2d695b561d/backend/open_webui/main.py#L1721-L1732
While `base_model_id` is part of `ModelModel`, it's not part of the params that are being used there it seems
https://github.com/open-webui/open-webui/blob/6c159a97b7efdfdbfa262ebd26823a2d695b561d/backend/open_webui/models/models.py#L86-L89
As a consequence, `model` and `form_data['model']` stay as their current values and not the fallback model, which fails downstream in the pipeline. I also experimented with forcing that block to run by manipulating the code directly on my deployment, and it does proceed to processing the chat, but fails somewhere else downstream more silently -- perhaps for reasons related to the original problem described here happening elsewhere.
GiteaMirror
added the bug label 2026-05-15 15:42:51 -05:00
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Originally created by @castielwaverly on GitHub (Mar 8, 2026).
Original GitHub issue: https://github.com/open-webui/open-webui/issues/22456
Check Existing Issues
Installation Method
Docker
Open WebUI Version
v0.8.9
Ollama Version (if applicable)
v0.17.4
Operating System
Alpine 3.23
Browser (if applicable)
Firefox
Confirmation
README.md.Expected Behavior
When I have enabled fallbacks and specified a default fallback model, the fallback gets used when the current base model of my custom model is unavailable.
Actual Behavior
When I have enabled fallbacks and specified a default fallback model, I get a
404: Model not founderror when the current base model of my custom model is unavailable.Steps to Reproduce
ollama-aandollama-bollama-a, e.g.ollama-a/gpt-oss:20bollama-b, e.g.ollama-b/ministral-3:3bollama-a/gpt-oss:20bcorrectly.ollama-ainstance.Logs & Screenshots
Additional Information
This is happening because
model_info_params.get("base_model_id")seems to be missing in all situations (instance down or not), so this entire block gets skipped:https://github.com/open-webui/open-webui/blob/6c159a97b7efdfdbfa262ebd26823a2d695b561d/backend/open_webui/main.py#L1734-L1741
This model info comes from the global config as the base, with specifics overwritten by the model params
https://github.com/open-webui/open-webui/blob/6c159a97b7efdfdbfa262ebd26823a2d695b561d/backend/open_webui/main.py#L1721-L1732
While
base_model_idis part ofModelModel, it's not part of the params that are being used there it seemshttps://github.com/open-webui/open-webui/blob/6c159a97b7efdfdbfa262ebd26823a2d695b561d/backend/open_webui/models/models.py#L86-L89
As a consequence,
modelandform_data['model']stay as their current values and not the fallback model, which fails downstream in the pipeline. I also experimented with forcing that block to run by manipulating the code directly on my deployment, and it does proceed to processing the chat, but fails somewhere else downstream more silently -- perhaps for reasons related to the original problem described here happening elsewhere.@tjbck commented on GitHub (Mar 8, 2026):
Addressed in dev.
@Classic298 commented on GitHub (Mar 8, 2026):
https://github.com/open-webui/open-webui/commit/c97767424f6ac7daf61daa84e15cdb10f1965d36