dify - 💡(How to fix) Fix Plugin with model-selector parameter fails: "The selector must be a dictionary" after upgrading to 1.14.0 [2 comments, 3 participants]

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Dify version

1.14.0

Cloud or Self Hosted

Self Hosted (Docker)

Steps to reproduce

1. Install any tool plugin that uses a model-selector type parameter in its YAML definition, for example:

parameters:

• name: model type: model-selector scope: llm required: true form: form

1. Configure the plugin in a workflow, select a model (e.g. DeepSeek deepseek-chat).
2. Run the workflow / invoke the tool.

✔️ Expected Behavior

The model-selector parameter should be passed to the plugin as a dictionary (as it was in v1.13.x), and the tool should invoke the selected LLM successfully.

❌ Actual Behavior

The tool invocation fails immediately with:

Failed to invoke tool: The selector must be a dictionary.

The error is thrown at the framework level (parameter deserialization), before the plugin's _invoke() method is ever called. No plugin-side fix is possible.

The actual parameter value passed by Dify shows the model field is serialized as a string instead of a dictionary:

{ "model": "{'provider': 'langgenius/deepseek/deepseek', 'model': 'deepseek-chat', 'model_type': 'llm', 'mode': 'chat', 'completion_params': {}}" }

This is a breaking regression — ALL tool plugins using model-selector parameters are affected after upgrading to 1.14.0.

Related:

• Dify Community Forum: https://forum.dify.ai/t/1-14-0-bug-failed-to-invoke-tool-the-selector-must-be-a-dictionary/1873
• Previous related issues: #22341, #22342, #22343