Erlang/OTP 26.0-rc1 has been released

Please provide feedback:

Erlang/OTP 26.0-rc1 is the first release candidate of three before the OTP 26.0 release.

The intention with this release is to get feedback from our users. All feedback is welcome, even if it is only to say that it works for you.
We encourage users to try it out and give us feedback either by creating an issue here Issues · erlang/otp · GitHub or by posting to Erlangforums.

All artifacts for the release can be downloaded from the Erlang/OTP Github release and you can view the new documentation at Erlang/OTP 26.0. You can also install the latest release using kerl like this: kerl build 26.0-rc1 26.0-rc1.

Erlang/OTP 26 is a new major release with new features, improvements as well as a few incompatibilities. Some of the new features are highlighted below.

Many thanks to all contributors!

Below are some highlights of the release:


The Shell

There are a lot of new features and improvements in the Erlang shell:

  • auto-complete of variables, record names, record fields names, map keys, function parameter types and filenames.
  • Open external editor in the shell to edit
    the current expression.
  • defining records (with types), functions, specs and types in the shell.

New terminal

  • The TTY/terminal subsystem has been rewritten.
    Windows users will notice that erl.exe has the same
    functionality as a normal Unix shell and that werl.exe is just a
    symlink to erl.exe. This makes the Windows Erlang terminal
    experience identical to that of Unix.

Compiler and JIT optimizations:

  • Creation and matching of binaries with segments of fixed sizes have been optimized.

  • Creation and matching of UTF-8 segments have been optimized.

  • Appending to binaries has been optimized.

  • The compiler and JIT now generate better code for creation of small maps where all keys
    are literals known at compile time.

  • Thanks to the optimizations above the performance of the base64 module has been
    significantly improved. For example, on an x86_64 system with the JIT both encode and
    decode are almost three times faster than in Erlang/OTP 25.


  • Map comprehensions as suggested in EEP 58 has now been

  • Some map operations have been optimized by changing the
    internal sort order of atom keys. This changes the
    (undocumented) order of how atom keys in small maps are
    printed and returned by maps:to_list/1 and maps:next/1.
    The new order is unpredictable and may change between
    different invocations of the Erlang VM.

  • Introducing the new function maps:iterator/2 for creating an interator
    that return the map elements in a deterministic order.
    There are also new modifiers k and K for the format
    string in io:format() to support printing map elements


  • Dialyzer has a new incremental mode that be invoked by
    giving the --incremental option when running Dialyzer.
    This new incremental mode is likely to become the
    default in a future release.

Misc ERTS, Stdlib, Kernel, Compiler

  • Multi time warp mode is now enabled by default.
    This assumes that all code executing on the system is
    time warp safe.

  • Support for UTF-8 atoms and strings in the NIF
    interface including new functions enif_make_new_atom,
    enif_make_new_atom_len and enif_get_string_length.

  • The BIFs min/2 and max/2 are now allowed to be used in
    guards and match specs.

  • Improved the selective receive optimization, which can
    now be enabled for references returned from other
    functions. This greatly improves the performance of
    gen_server:send_request/3, gen_server:wait_response/2,
    and similar functions.

  • New trace feature call_memory. Similar to call_time
    tracing, but instead of measure accumulated time in
    traced functions it measures accumulated heap space
    consumed by traced functions. It can be used to compare
    how much different functions are contributing to
    garbage collection being triggered.

  • It is no longer necessary to enable a feature in the
    runtime system in order to load modules that are using
    it. It is sufficient to enable the feature in the
    compiler when compiling it.

  • inet:setopts/2 has got 3 new options: reuseport, reuseport_lb and exclusiveaddruse.

  • Fix so that -fno-omit-frame-pointer is applied to all
    of the Erlang VM when using the JIT so that tools, such
    as perf, can crawl the process stacks.

  • In the lists module, the zip family of functions now takes
    options to allow handling lists of different lengths.

  • Added the zip:zip_get_crc32/2 function to retrieve the
    CRC32 checksum from an opened ZIP archive.
    gen_server optimized by caching callback functions

  • The modules Erlang DNS resolver inet_res and helper
    modules have been updated for RFC6891; to handle OPT RR
    with DNSSEC OK (DO) bit.

  • Introduced application:get_supervisor/1.

  • Cache OTP boot code paths, to limit how many folders
    that are being accessed during a module lookup. Can be
    disabled with -cache_boot_path false.


  • Support for Kernel TLS (kTLS), has been added to the
    SSL application, for TLS distribution (-proto_dist
    inet_tls), the SSL option {ktls, true}.

  • Improved error checking and handling of ssl options.

  • Mitigate memory usage from large certificate chains by
    lowering the maximum handshake size. This should not
    effect the common cases, if needed it can be configured
    to a higher value.

  • For security reasons the SHA1 and DSA
    algorithms are no longer among the default values.

  • Add encoding and decoding of use_srtp hello extension
    to facilitate for DTLS users to implement SRTP

For more details about new features and potential incompatibilities see the readme