## TL;DR

[run-llama/llama_index#20278]: the LlamaIndex Vertex AI vector store uploads batch-update files to gs://bucket/{uuid}/ but Vertex looks for them at gs://bucket/index/{uuid}/.

## Steps

1. [run-llama/llama_index#20278]: the LlamaIndex Vertex AI vector store uploads batch-update files to gs://bucket/{uuid}/ but Vertex looks for them at gs://bucket/index/{uuid}/. Workaround: catch the ValueError, extract the UUID from the message, copy the uploaded blobs from the {uuid} prefix into the index/{uuid} prefix with the Storage client, then retry. General checklist for index updates: index deployed on an Index Endpoint, dimensions matching the deployed index config, service account with Vertex AI permissions.

## When to use

Use this skill when you run into "Vertex AI Vector Search: GCS path mismatch on index update (llama-index)".

## When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

## Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

## Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.