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@dkfellows dkfellows released this 13 May 12:47
· 482 commits to main since this release
core-8-6-18
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Tcl/Tk 8.6.18 Release Announcement

May 11, 2026

The Tcl Core Team is pleased to announce the 8.6.18 releases of the Tcl dynamic language and the Tk toolkit. We intend these to be the final releases of Tcl 8.6 and Tk 8.6. Both Tcl and Tk have successor major release sequences in active supported development. As of this release date, users of Tcl and Tk are encouraged to move to Tcl 9.0.3 and Tk 9.0.3.

With development of Tcl/Tk 8.6 at an end, we are no longer soliciting bug reports and patches for these lines of development. Please only report issues that are believed so severe in nature that they would justify re-opening a closed development sequence.

Where to get the new releases:

Tcl/Tk 8.6.18 sources are freely available as open source from the Tcl SourceForge project's file distribution area:

Note

The files attached here are a subset of those.

This distribution is source code only. We keep links to some third parties offering pre-built binaries for various systems here:

Tcl/Tk 9 releases:

The latest stable releases of Tcl and Tk are versions 9.0.3, released November 13, 2025. Users of Tcl/Tk 8.6 are encouraged to migrate to the new releases, where continued development efforts are focused.

For additional information:

Please visit the Tcl Developer Xchange web site:

This site contains a variety of information about Tcl/Tk in general, the core Tcl and Tk distributions, Tcl development tools, and much more.

Summary of Changes since Tcl/Tk 8.6.17:

This is a patch release, so it primarily includes bug fixes and corrections to erratic behavior. Highlighted changes are noted below. The changes file at the root of the source tree contains a more complete list. The Timelines of all changes are online.

Changes to Tcl:

  • Fix crashes or hangs or undefined behavior in...

    • crash on exit due to faulty asm code in DllMain
    • proc creation during namespace deletion
    • Tcl_PushVarName()
    • SetScriptLimitCallback()

  • Don't let empty regexp suppress errors of variable resolution

  • Don't let [string trim] produce invalid utf-8.

  • Installation on Windows now includes manpages and pkg-config.

  • Updated bundled packages, libraries, standards, data

    • Itcl 4.3.7
    • sqlite3 3.53.0
    • Thread 2.8.13
    • TDBC* 1.1.13
    • platform 1.1.0
    • http 2.9.9
    • tcltest 2.5.11
    • dde 1.4.6
    • tzdata 2026b
    • Unicode 17
    • zlib 1.3.2
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