.NET Driver release notes for 2026¶

See .NET Driver for documentation.

Version 6.0.0 (August 10, 2026)¶

Breaking Changes¶

• Surface-level connection exceptions occurring in OpenAsync and CloseAsync are now thrown directly, without wrapping inside AggregateException.
• A fault that occurs while closing a connection now leaves it in the Broken state instead of Closed.
• A fault that occurs while opening a connection with OpenAsync no longer leaves the connection stuck in the Connecting state. Retry patterns on such failures are now possible without recreating the connection object.

New features and improvements¶

• Added CancellationToken support to chunk download and parsing pipeline. Query result fetching now respects cancellation during both JSON and Arrow chunk parsing.
• Reduced synchronization context capture in the library, minimizing the risk of deadlocks across different code execution paths.
• Replaced NUnit tests with Xunit to modernize and stabilize existing CI/CD setup.
• Improved handling of certificate serial number matching and performance of CRL checking.
• AWS Workload Identity Federation attestation now defaults to a SigV4-presigned GetCallerIdentity request and attestation through the STS GetWebIdentityToken path (returning a signed JWT) is available as an opt-in by setting the SNOWFLAKE_ENABLE_AWS_WIF_OUTBOUND_TOKEN=true environment variable.
• OpenAsync method of SnowflakeDbConnection now throws the original exception on failure instead of wrapping it in an AggregateException.
• CloseAsync now throws the original exception on failure instead of wrapping it in an AggregateException.
• Upgraded AWSSDK.S3 dependency. Now getting the object header invokes a HEAD S3 call instead of GET.
• Added AllowNumberOverflowAsString connection property. When set to true, numeric values that exceed the range of System.Decimal (or a narrower integer type) are returned as strings from GetValue() instead of throwing OverflowException.

Bug fixes¶

• Fixed non-Windows builds with added NativeLibrary items in their transitively built projects that were no longer available to copy to the output directory.
• OpenAsync method of SnowflakeDbConnection now resets its state to Closed on failures.
• CloseAsync method of SnowflakeDbConnection now resets its state to Closed on cancellation and Broken on failures.
• Fixed session creation token leak when GetSessionAsync is cancelled.
• Fixed incorrect DateTime conversion for timestamps preceding Unix epoch (1970-01-01) when fractional seconds are present.
• Fixed an unnecessary second PUT (stage re-resolution) per file during GCS uploads when the server scopes upload credentials with an access token.

Version 5.7.0 (June 12, 2026)¶

New features and improvements¶

• Improved input handling in ChangeDatabase by using parameterized queries.
• Improved input validation in QueryResultsAwaiter with stricter UUID format checks.

Bug fixes¶

• Fixed OverflowException when converting REST response with master token validity more than approximately 9.1 hours.
• Added path traversal protection for file downloads: destination paths are now validated against the target base directory before writing.
• Replaced use of System.Random with a cryptographically secure random number generator in the authenticator challenge/proof key generation and file transfer encryption key/IV generation.

Version 5.6.0 (May 20, 2026)¶

New features and improvements¶

• Added .NET 10 support. Changed LangVersion to C# 13.
• Added client-side telemetry instrumentation using System.Diagnostics.Activity (OpenTelemetry-compatible). When CLIENT_TELEMETRY_ENABLED=true (the default), the driver automatically instruments all command executions and their async variants, and sends telemetry data to Snowflake’s /telemetry/send endpoint. Activities are enriched with session context (warehouse, role, database, session ID) and report success or error status with exception details.
• Added the public StartActivity extension method on SnowflakeDbCommand for creating custom client-defined telemetry activities. Custom activities use a separate activity source (Client_custom_activity).
• Added DbType.AnsiStringFixedLength to the set of types mapped to Snowflake TEXT, matching existing support for AnsiString, String, and StringFixedLength.
• Extended login-request telemetry with libc detection (LIBC_FAMILY, LIBC_VERSION). On Linux, the driver now reports whether the runtime uses glibc and includes the library version.
• Reduced the default maximum CRL download size from 200 MB to 20 MB, aligning with other Snowflake drivers.

Bug fixes¶

• Fixed handling of transient server issues that resulted in sending a truncated JSON response.
• Fixed an issue where connections with sessions that no longer existed on the server were reused from the pool, which previously caused repeated failures until the connection expired on its own. These connections are now detected and removed from the pool.

Version 5.5.0 (April 13, 2026)¶

New features and improvements¶

• The driver now includes SPCS_TOKEN in login requests when running inside a Snowpark Container Services (SPCS) container (detected via the SNOWFLAKE_RUNNING_INSIDE_SPCS environment variable).
• Extended login-request telemetry with cloud platform and environment detection (AWS Lambda, EC2, Azure VM/Functions, GCE/Cloud Run, GitHub Actions). Detection runs once at startup in the background within a 200ms timeout. You can disable this feature by setting the SNOWFLAKE_DISABLE_PLATFORM_DETECTION environment variable.
• Added the workloadIdentityImpersonationPath connection parameter for authenticator=WORKLOAD_IDENTITY, which allows workloads to authenticate as a different identity through transitive service account impersonation.
• Added the HonorSessionTimezone connection parameter (default: false). When set to true, TIMESTAMP_LTZ values honor the session TIMEZONE parameter (set using ALTER SESSION SET TIMEZONE) instead of the local machine timezone. This will become the default behavior in a future major release.

Bug fixes¶

• Fixed an issue where idle sessions were not evicted from the connection pool when closing them fails.
• Fixed an issue where sessions that receive HTTP 401 during query execution were returned to the connection pool.
• Fixed GetResultsFromQueryIdAsync not aborting queries on the server when a CancellationToken is cancelled. Previously, only client-side polling stopped while queries continued running on Snowflake.
• Fixed Azure GET (download) operations incorrectly reporting an UPLOADED result status instead of DOWNLOADED when the server returns presigned URLs for an encrypted stage.
• Fixed query context cache not being updated when the server returns queryContext in a failed query response.
• Improved CRL issuer validation: issuer names are now compared using DER encoding (avoiding string-form mismatches such as S= vs ST=), and the CRL’s Authority Key Identifier is verified against the issuing CA’s Subject Key Identifier when both extensions are present.

Version 5.4.1 (February 17, 2026)¶

New features and improvements¶

• Extended login-request telemetry with Linux distribution details parsed from /etc/os-release.

Bug fixes¶

• Fixed IndexOutOfRangeException in Arrow result chunk processing by adding retry state cleanup, batch integrity validation, and defensive bounds checking in ExtractCell().
• Fixed IndexOutOfRangeException when reading NUMBER/DECIMAL columns with scale greater than 9 in Arrow result format.

Version 5.4.0 (February 05, 2026)¶

New features and improvements¶

• Added support for Red Hat Enterprise Linux (RHEL) 9.
• Added support for the DECFLOAT data type (returned as string to preserve full precision).

Bug fixes¶

• Fixed IndexOutOfRangeException in Arrow result processing when empty batches are returned by the Snowflake backend.

Version 5.3.0 (January 07, 2026)¶

New features and improvements¶

• Introduced a shared library for extended telemetry to identify and prepare the testing platform for native Rust extensions.

Bug fixes¶

• None.