First release of the 6.38 series. 🗒️ Release notes 💾 Install instructions We are proud to announce the Development release ROOT 6.38.00 🏆 The focus for this release was on expanding usability from Python and interoperability with its ecosystem, data analysis and modernisation. However, there is much more than that: ease of installation, runtime performance, stability (>250 items in our trackers have been addressed). See the full release notes and highlights below! 📦 Distribution In alpha mode, you can install 6.38 releases with pip on Linux: pip install root 🚀 📈 RDataFrame. Ergonomics: You don't need to write template arguments for Snapshot any more, i.e. myDf.Snapshot(... You can snapshot systematic variations to TTree in experimental mode. See systematic variations for the details! Distributed RDataFrame: RNTuples are treated internally as TTrees. Without API changes, your processing of RNTuples will be even faster than before! 🐍 Python Interface In RDataFrame, you can pass to Define and Filter a set of Python functions wider than before. An enhanced Unified Histogram Interface (UHI) implementation is now even more stable, thanks to a reinforced testing suite extending the UHI testing helper. 7️⃣ ROOT7 New highly performant histograms are available for testing: see these examples! ROOT::Experimental::RFile, a minimal and modern interface to ROOT files, is there! 💾 RNTuple Clarity: you can support RNTuple with the classic browser, profiting from several visual improvements, including a new treemap visualization of field sizes. Parallelism: The parallel writer became part of the stable API. See it in action in this example. Performance: (vectors of) fixed-size arrays are now treated in bulk Usability: automatic schema evolution is now akin to the classic I/O behavior. You can read expert documentation in tree/ntuple/doc/SchemaEvolution.md. 🧑🏽‍💻 C++ Interpreter The LLVM powering Cling has been upgraded to version 20: more runtime performance and features thanks to the new compiler! You can use SYCL interactively if you build ROOT with -Dexperimental_adaptivecpp=ON 📊 RooFit With the RooMultiPdf, you can minimize floating categorical variables, e.g. for models with variables that toggle between different background shapes. Please note that 6.38 is a short term support release. As such, it is not meant to be used for data taking. It will be superseded by the 6.40 release, which is foreseen in May 2026. Patch releases of 6.38 will be provided until June 2028.