Document Store preview Chunks hangs indefinitely and returns "undefined" on Flowise Cloud 3.1.2

[iqqie78-prog]

Describe the bug

I am experiencing an issue with Document Store preview and upsert on Flowise Cloud version 3.1.2.

When trying to preview chunks in a Document Store, the loader keeps spinning for several minutes and eventually returns “undefined”.

This happens even with:

a completely fresh account
a completely empty workspace
no Agentflows or Chatflows
no vector database configured
no embeddings configured
a simple hello world .txt file
using Text File Loader
using Recursive Character Text Splitter

The loader keeps spinning indefinitely and eventually returns “undefined”. Additionally, if I skip “Preview Chunks” and try to upsert directly, the status remains yellow indefinitely and nothing gets processed or indexed.
State Document store Stale

What I already tried:

clearing browser cache
incognito mode
different browser
restarting computer
deleting all document stores/flows
creating a completely new Flowise Cloud account

The issue persists across all attempts.

Could someone confirm whether this is a known issue or if there is a workaround available?

Thank you.

To Reproduce

1. Create a new Document Store
2. Select Text File Loader
3. Upload a simple .txt file containing only “Hello world”
4. Add Recursive Character Text Splitter
5. Click “Preview Chunks”

Expected behavior

Chunks should preview normally within seconds.

Screenshots

Flow

No response

Use Method

None

Flowise Version

3.1.2

Operating System

Windows

Browser

Chrome

Additional context

No response

[Umesh042005]

I tried reproducing this locally on v3.1.2 — Preview Chunks works fine on local setup. This might be Cloud-specific. Can someone from the team confirm if there's a Cloud-side config difference?

[iqqie78-prog]

The Document Store preview now works, but when I define an embeddings model and vector database and then try to upsert, the process fails with a 500 error.

_**_Error message:

Oh snap!
The following error occurred when loading this page.
Status: 500
Error: documentStoreServices.insertIntoVectorStoreMiddleware - Error: documentStoreServices.insertIntoVectorStore - Error: documentStoreServices.insertIntoVectorStoreWorkerThread - TypeError: Cannot read properties of undefined (reading '0')
Please retry after some time. If the issue persists, reach out to us on our Discord server.
Alternatively, you can raise an issue on Github.**_

The document chunks should be embedded and inserted into the vector database successfully. I have tried diffrent embeddingsmodels but the page fails with Status 500 and the error:
TypeError: Cannot read properties of undefined (reading '0')

When I go back to my Document store the status is Upserting. When I go to 'More Actions' only thing I can do is Delete my Document Store, the other actions are disabled.

Could someone confirm whether this is a known issue and if there is a workaround available?

[Umesh042005]

Hey! I looked into this locally, here's what I found.

The 500 Upsert Error

Traced the error path through the backend:

documentStoreServices.insertIntoVectorStoreMiddleware
  → insertIntoVectorStore
    → insertIntoVectorStoreWorkerThread
      → _createEmbeddingsObject / _createVectorStoreObject  ← CRASH HERE

Both _createEmbeddingsObject and _createVectorStoreObject are directly accessing component properties without checking if the component exists first:

// _createEmbeddingsObject
const embeddingComponent = componentNodes[data.embeddingName]
// no null check — if embeddingName is undefined, next line crashes
const embeddingNodeData = {
    ...embeddingComponent.name  // 💥 Cannot read properties of undefined
}

// _createVectorStoreObject
const vStoreNodeInstanceFilePath = componentNodes[data.vectorStoreName].filePath
// same issue — no null check before accessing .filePath
// 💥 Cannot read properties of undefined (reading '0')

Proposed Fix

Just need to add null checks before accessing these components:

// In _createEmbeddingsObject
const embeddingComponent = componentNodes[data.embeddingName]
if (!embeddingComponent) {
    throw new InternalFlowiseError(
        StatusCodes.INTERNAL_SERVER_ERROR,
        `Embedding component "${data.embeddingName}" not found in component nodes`
    )
}

// In _createVectorStoreObject
const vectorStoreComponent = componentNodes[data.vectorStoreName]
if (!vectorStoreComponent || !vectorStoreComponent.filePath) {
    throw new InternalFlowiseError(
        StatusCodes.INTERNAL_SERVER_ERROR,
        `Vector store "${data.vectorStoreName}" not found in component nodes`
    )
}
const vStoreNodeInstanceFilePath = vectorStoreComponent.filePath as string

This way instead of a confusing undefined crash, users get a clear error message telling them exactly what’s missing.

Working on a PR for this, will link it here once ready!