---
title: "Release highlights: 1.28"
description: Release highlights provide a concise overview of the most important new features, improvements, and fixes in a software update.
keywords: [dlt, data-pipelines, etl, release-notes, data-engineering]
---

# Release highlights: 1.28

## Breaking changes

- **Python 3.9 support dropped.** Python 3.9 reached end of life, so dlt no longer supports it. The minimum is now Python 3.10 ([#4074](https://github.com/dlt-hub/dlt/pull/4074)). Install this release on Python 3.10 or newer, and stay on an earlier dlt version if you cannot upgrade the interpreter (since 1.28.1).
- **`refresh="drop_data"` keeps files on Delta and Iceberg.** Truncating a Delta or persistent-catalog Iceberg table is now a transactional delete ([#4051](https://github.com/dlt-hub/dlt/pull/4051)) that keeps its files for time travel, so `refresh="drop_data"` no longer frees storage. Pipelines that relied on it to reclaim disk must now run `vacuum` explicitly.
- **`replace` truncates empty and orphaned tables.** Tables of a `replace` resource that receive no data in a run, including nested, dynamic-name, and variant tables, are now consistently truncated ([#4010](https://github.com/dlt-hub/dlt/pull/4010)). Previously they could keep stale rows across reloads, so pipelines relying on that leftover data will now see those tables emptied.

## Configurable CSV encoding

You can now set the encoding of the CSV files dlt writes with a new `encoding` option (default `utf-8`) under `[normalize.data_writer]` ([#4045](https://github.com/dlt-hub/dlt/pull/4045)). Use `utf-8-sig` for an Excel BOM or `latin-1`/`cp1252` for legacy importers, and `encoding_errors` to control how unrepresentable characters are handled.

```toml
[normalize.data_writer]
encoding="utf-8-sig"
encoding_errors="replace"
```

## Reliable full refresh with the `refresh` option

`refresh` is now the recommended way to fully reload data. Set `refresh="drop_data"` to truncate the selected resources' tables and reset their incremental state, leaving other tables intact ([#4010](https://github.com/dlt-hub/dlt/pull/4010)). The old `write_disposition="replace"` switch for a full refresh is deprecated. Truncation now reliably covers nested, dynamic-name, and variant tables.

```py
import dlt

@dlt.resource
def users():
    yield {"id": 1, "name": "alice"}

pipeline = dlt.pipeline("app", destination="duckdb")
# full refresh: truncate the resource's tables and reset incremental state
pipeline.run(users(), refresh="drop_data")
```

## Refreshable cloud credentials on long-running loads

Default cloud credential chains (AWS, Azure, GCP) are now handed to the underlying access libraries, fsspec, the object_store crate, pyiceberg, and DuckDB, so each refreshes tokens through its own provider chain instead of a frozen snapshot ([#4056](https://github.com/dlt-hub/dlt/pull/4056), [#4021](https://github.com/dlt-hub/dlt/pull/4021)). This stops `ExpiredToken` failures on long reads and loads that use temporary credentials, while static keys and explicit sessions stay frozen.

## NUL characters stripped from insert-values string literals

String values containing a NUL byte (the ASCII null character, `0x00`), common in data from MongoDB, previously produced invalid INSERT statements on Postgres, Redshift, and DuckDB. dlt now strips NUL from escaped string literals so those rows load ([#4086](https://github.com/dlt-hub/dlt/pull/4086)), and splits multi-row inserts on newlines only so values holding other line separators stay intact.

## Correct temporal precision from newer connectorx

With a newer connectorx, the `sql_database` connectorx backend returns timestamps and times at nanosecond precision through its `arrow_stream` type instead of the older millisecond `date64`. dlt now normalizes every connectorx temporal column to the microsecond precision destinations expect, truncating losslessly ([#3996](https://github.com/dlt-hub/dlt/pull/3996)).

## Shout-out to new contributors

Big thanks to our newest contributors:

* [@0ywfe](https://github.com/0ywfe)
* [@Analect](https://github.com/Analect)
* [@wtfashwin](https://github.com/wtfashwin)
* [@nuetu](https://github.com/nuetu)
* [@tderk](https://github.com/tderk)

**Full release notes**

[View the 1.28.0 release notes](https://github.com/dlt-hub/dlt/releases/tag/1.28.0)