Intermittent TCP Provider: Error code 0x68 (08S01) during bulk INSERT full loads into Fabric SQL DB

[Oviwan]

Hi Fabric community

We are experiencing intermittent connection failures when performing full data loads using bulk INSERT statements into a SQL Database in Microsoft Fabric.
The error typically occurs during COMMIT, after a large bulk insert has been running successfully for some time.

Error message

DBMS error [TCP Provider: Error code 0x68. Communication link failure].
DBMS error number [104].
SQL State [08S01].
DBMS version [12.00.9114].
Driver [Microsoft][ODBC Driver 18 for SQL Server].
Last query [commit].

Scenario

• Target: SQL Database in Microsoft Fabric
• Load type: Full load
• Method: Bulk INSERT / INSERT BULK statements
• Volume: Millions of rows per table
• Driver: ODBC Driver 18 for SQL Server

The bulk insert runs for a while and then fails sporadically, usually:

• towards the end of a large transaction
• at COMMIT time
• without a deterministic pattern or reproducible table-specific issue

A simple retry often succeeds but not always, which suggests a transient connectivity issue rather than a data or schema problem.

 Questions

We would like to understand whether this can be mitigated on the Fabric SQL Database side, not only in the application:

1. Are there any Fabric SQL or database-level settings to:
   • increase connection or transaction timeouts?
   • extend allowed execution time for long-running bulk operations?
2. Are there any limits or behaviors specific to Fabric SQL that could cause connections to be dropped during large bulk INSERT + COMMIT operations?
3. Is TCP Provider: Error code 0x68 (SQLState 08S01) considered a known transient condition when running heavy bulk loads in Fabric SQL (e.g. due to gateway, proxy, or capacity constraints)?

Goal

The goal is to make large one-time full loads via bulk INSERT stable and predictable in Fabric SQL, without relying purely on retries after failed commits.

Any guidance from Microsoft or others running large-scale bulk ingestion into Fabric SQL would be very helpful.

Thanks in advance!

Regards

[HugoQueiroz-MSF]

@Oviwan T

TCP Provider: Error code 0x68 (SQLState 08S01) typically indicates an unexpected connection drop (it can be several different things). To better understand your specific scenario, we would need additional details about the source system and, ideally, its logs as well. In this case, could you please open a support request so we can investigate in more detail?

As general best practices, consider reducing the transaction scope and duration (for example, committing smaller batches), implementing retry logic, and staging the inserts, which can also help improve reliability and performance.