# DuckDB v1.5.1 — Release & Upgrade Intelligence
- **Product:** DuckDB (https://duckdb.org)
- **Version:** v1.5.1
- **Released:** Mar 23, 2026
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/duckdb/updates/v1.5.1/

## Executive Summary (TL;DR)
DuckDB v1.5.1. Source highlight: This is a bug fix release for various issues discovered after we released v1.5.0.

## New Features
- [Dev] Add internal exception for misuse of `MultiFileReader` method
- Add framework to test two DuckDB versions
- Re-add accidentally removed -jsonlines command line parameter
- add structured Path objects, update joinpath: normalize, support url/…
- When stress testing FORCE_ASYNC, add the relevant error messages
- Add missing expression traversal in `merge into` binding

## Improvements
- Improve estimate when first Parquet file is almost empty, and get exact cardinality count when we are using union by name
- Use cached Parquet metadata to improve cardinality estimates over Parquet files

## Bug Fixes
- [Regression v1.5] Fix INTERNAL Error in UnnestRewriter for deeply nested struct UNNEST
- fix(storage): prevent TrimFreeBlocks from zeroing concurrently alloca…
- fix: buffer overread in Arrow dictionary conversion with NULLs - fixes crash.
- Fix DuckFuzz #4325
- Fix decorrelation delim index bug
- Fix two minor shell bugs: Avoid mutating rendered strings and avoid p…