OMNeT++ 6.3 (November 2025)

This release focuses on incremental improvements and refinements rather than introducing major new features. Key enhancements include Analysis Tool improvements such as configurable bin setup for "histogram from vectors" charts, global menu support in Qtenv, enhanced dark theme support throughout the IDE, and various other usability and stability improvements across the platform.

Simulation kernel:

  • The cCommBuffer classes and parsimPack()/parsimUnpack() functions are now always available, regardless of whether the simulation kernel was compiled with parsim support. Previously, these functions would throw "parsim not available" exceptions when used in non-parsim builds. This change enables their use in other contexts such as fingerprint calculations. The cCommBuffer classes have been moved out of sim/parsim/ and are included even with WITH_PARSIM=no configuration. Additionally, cCommBufferBase now provides setMode()/getMode() methods to support non-parsim use cases.
  • NED functions now have access to the target parameter being assigned, which is particularly important for deep assignments where the target module cannot be inferred from the context module. This was implemented by adding a targetPar field (type cPar*) to cExpression::Context, replacing the previous parName field.
  • Improved platform support for the DEBUG_TRAP macro, particularly on ARM processors running in x86_64 emulation mode, by utilizing __builtin_debugtrap() when available with gcc and clang compilers.
  • Made DemuxFilter demux label generation more easily customizable by adding a protected getDemuxLabel() method that can be overridden in subclasses to define custom labeling logic.

MSG files, opp_msgc:

  • Improved naming flexibility for targeted cplusplus blocks in classes marked with @customize. The code generator now accepts both Foo::Foo_Base and Foo::Foo syntax when targeting constructors, copy constructors, and destructors, making the feature more intuitive to use.
  • Several bug fixes.

Cmdenv:

  • Enhanced event banners in normal (non-express) mode to include event information and fingerprint data for improved debugging visibility.
  • Fixed a bug where the "Refusing to run abstract configuration" error did not cause the program to exit with a nonzero exit code, which could prevent proper error detection in automated scripts.

Qtenv:

  • Added a "Move menu to the toolbar" checkbox in the Preferences dialog. When this option is enabled, the window's menu bar is hidden, and a "hamburger" icon is displayed on the toolbar instead. On systems where global menu is used (macOS and certain Linux desktop environments), it fixes a usability issue that the local menu was unavailable from the application window -- now it is available via the hamburger menu. On other systems, enabling this option may be used to free up vertical space when needed.
  • Renamed columns in the log inspector for greater clarity: "Event#" was changed to "Sender Event#", and "Time" was changed to "Sending Time" to better reflect the displayed information.
  • Improved dark theme support, particularly for styled text rendering in the Log view, providing better readability and visual consistency.
  • Made application style configurable through the Preferences dialog by adding an "Application style" combo box. Additionally, a new "Use the Fusion default color palette" checkbox was added to help overcome potential readability issues in dark mode.
  • Fixed a bug where log messages written during network initialization were not shown in the log viewer, and the network graphics was not displayed in the main area, when an exception occurred during network initialization.
  • Further bug fixes and improvements.

Fingerprints:

  • Added two new fingerprint ingredients to provide more granular control over fingerprint computation: message control info ('g') and message contents ('b'). The message control info ingredient includes control information objects attached to arriving messages. The message contents ingredient incorporates the core message data, excludes both control info and technical bookkeeping fields from the last transmission, and it is insensitive to simulation time and the identity of the sender/receiver modules. Both ingredients use parsimPack() to serialize objects into byte arrays for fingerprint inclusion. These additions enable more detailed fingerprint-based regression tests and can help detect subtle differences in message traffic that might not be captured by other fingerprint ingredients.

opp_makemake:

  • Fixed race condition that could occur with parallel builds when the -B option is used, ensuring more reliable compilation of large projects.

opp_neddoc:

  • Fixed a bug that prevented the opp_neddoc command from working properly (#1439). The problem was caused by an unintentional access of the workspace, which does not exist in headless mode.

Python library:

  • In omnetpp.scave.utils, histogram_bin_edges() was replaced with a more capable implementation to support the new "Histogram Bins" page in the "Histogram from vectors" chart template.
  • Several bug fixes and minor improvements.

Analysis Tool:

  • Made histogram bins configurable in "Histogram from vectors" charts by adding a new "Histogram Bins" page to the chart configuration dialog. Users can now specify any combination of bin width, number of bins, and histogram interval upper/lower bounds. The histogram calculation uses smart defaults for unspecified parameters, and manual specification of bin edges is also supported.
  • Improved the logic for determining when to preserve the current view versus zooming out fully after re-running chart scripts. This enhancement makes the Apply button in the Chart Properties dialog much more useful, as users no longer need to close the dialog and click the "Home" button to see updated plots after making non-cosmetic changes.
  • The Console view now automatically opens when launching the chart script editor, displaying relevant output such as warnings and print() statement results. This provides immediate access to debugging information without being intrusive, since the chart script editor is typically opened infrequently and remains open during extended use.
  • In the 'CSV for Spreadsheet' export, added the 'weighted' and 'variance' columns to statistics and histogram output.
  • Added 'Module Display Path' column to Browse Data tables for better module identification. (Display path is the module path composed of module display names configured via display-name configuration options where available.)
  • Added 'Compare chart to template' link to the 'Reset to Template' dialog for easier comparison before resetting.
  • Fixed sorting issues affecting certain columns in Browse Data tables.
  • Reduced margins around data on native line plots for better space utilization and cleaner appearance.

Other IDE Components:

  • Added automatic freeze detection and recovery to prevent occasional IDE lockups. The IDE can sometimes become unresponsive due to internal conflicts where different parts of the system are waiting for each other. The new detection system automatically identifies when the IDE has frozen and attempts to recover by interrupting the conflicting processes. This should significantly reduce instances where users need to restart the IDE due to freezes.

    Note: This feature can be disabled by setting the environment variable OMNETPP_DISABLE_DEADLOCK_DETECTION if needed.

  • Improved dark theme support throughout the IDE. Affected areas are tab folders, custom-drawn tables used in the Analysis Tool and Sequence Chart Tool, and the color scheme of the XSWT Editor.
  • NED Editor: In the Properties dialog, replaced spinner controls with plain text fields. Spinners were problematic because they cannot reliably represent the "missing" value.
  • NED documentation generator: Made the navigation tree area resizable in the generated HTML. To resize, grab the handle at the bottom right corner of the navigation tree area.
  • C++ Development: Resolved race condition issues in generated Makefiles during parallel builds when the -B option is used, improving build reliability for large projects.
  • The IDE is now based on Eclipse 2025-09.

See ChangeLogs in individual folders for details.

Bugs fixed: https://github.com/omnetpp/omnetpp/issues?q=is%3Aissue+is%3Aclosed+milestone%3A6.3


What's New in OMNEST 6.2.0