Azure AI Search indexer works without skillset but fails with SQL connection error when adding embedding skillset
Hi everyone,
I'm trying to build a Databses Syncronization pipeline using Azure AI Search with SQL Server + Azure OpenAI embeddings, but I’m stuck on a very confusing issue.
I already isolated the problem and tested multiple components independently, but I still get a SQL connection error only when a skillset is added.
- Architecture I’m building
- SQL Server (hosted on Azure VM)
- Azure AI Search indexer
- Azure OpenAI embedding skillset
- Vector index
- What works
- SQL Data Source works
I created a SQL view and connected it as a data source:
✔ Indexer WITHOUT skillset works perfectly
✔ Data is successfully pulled from SQL
✔ Documents are indexed into Azure AI Search
- Embedding skillset works independently
I tested the skillset directly using:
- API
- Python SDK
✔ Azure OpenAI embedding generation works
✔ Skillset returns embeddings correctly
✔ No authentication issues
- Skillset creation works
I can create the skillset successfully via:
- Azure Portal
- Python SDK
- REST API
- Index + vector field works
✔ Vector index schema is correct
✔ HNSW profile configured
✔ Embedding field is properly defined (3072 dims)
- The problem
When I attach the skillset to the indexer, the indexer execution fails with:
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.)
Important observation
This ONLY happens when:
- skillset is attached to the indexer
But NOT when:
- indexer runs without skillset
- What I already tested
SQL connectivity
- SQL Server is reachable from my machine
- Port 1433 is open
- Connection works using pyodbc
- Indexer without skillset works
Azure OpenAI
- Embedding deployment works
- Skillset tested independently via REST
$test - No errors in embedding generation
Azure AI Search
- Indexer is created successfully via Python SDK
- Skillset is created successfully
- Index schema is valid
- What is confusing me
It looks like adding a skillset changes how the indexer connects to SQL Server.
But I don’t understand why:
- SQL works fine without skillset
- but fails when skillset is added
- even though embedding step should happen AFTER data is retrieved
I’ve been debugging this for a while and I’m starting to suspect this is network architecture related rather than configuration.
If anyone has experienced something similar, I’d really appreciate guidance 🙏