Knowledge Base node returns "preview" error in Simple Q&A pipeline

[vachy24]

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Dify version

1.13.2

Cloud or Self Hosted

Self Hosted (Docker)

Steps to reproduce

Create a new Knowledge Pipeline using the "Simple Q&A" default template
Configure a FILE-type data source
Run a test execution
Observe that:
✅ FILE node: Success
✅ Q&A PROCESSOR node: Success (outputs valid qa_chunks with question/answer fields)
❌ KNOWLEDGE BASE node: Failed with error: 'preview'

✔️ Expected Behavior

The Knowledge Base node should successfully ingest the processed QA pairs from the Q&A Processor and store them in the vector database.

❌ Actual Behavior

The node fails immediately with a minimal error message: 'preview' (no stack trace or detailed explanation).

[EndlessLucky]

@vachy24 Can I work on this issue?

[vachy24]

@EndlessLucky Sure! Feel free to work on this issue. 👍