Changelog for TUFLOW 2026.2.0

Release date: 30 June 2026

  1. General Notes
  2. Backwards Compatibility
  3. Bug Fixes
    1. Domain Construction
    2. 1D Network Domains – EPA SWMM
    3. Boundaries and Links
    4. Outputs and Check Files

General Notes

This is a bug fix release for TUFLOW 2026.0. This purpose of this release is to fix several bugs within TUFLOW 2026.0. For more details, see the Bug Fixes section below.

Starting with 2026.2.0, bug fix releases will increment the minor version number (i.e. the middle digit, in this case 2) rather than the patch version number (the last digit). This change allows users to retain all previous versions (with one exception, noted below) of TUFLOW when installing TUFLOW via an installer, such as the .msi installer on Windows.

Installers currently overwrite patch versions within the same minor stream (for example, installing 2026.0.1 replaces 2026.0.0). By moving bug fix releases to the minor version, users will have greater control and flexibility on which TUFLOW versions they wish to have on their computer.

Patch releases will still be used for security issues and critical bug fixes, but these are expected to be rare. Patch releases will increment the patch version number and the installer will continue to replace the previous version within the same minor stream.

The previous bug fix release, 2026.0.1, has been re-released as 2026.1.0 so users can retain 2026.0.0 when installing via an installer (hence this release is 2026.2.0).

Accompanying TUFLOW User Manual updates will still only be released for scheduled minor and major releases that contain feature updates, and will no releases will be made for bug fix releases.

Backwards Compatibility

It is not expected that the 2026.2.0 release would cause changes in results if upgrading from the 2026.0 release, except for the specifics of the bug fix listed below.

Bug Fixes

Domain Construction

  • Fixed a bug that could cause an unhandled Fortran exception when using a reporting location polygon that selected a 1D node. This bug was likely triggered by the 2026.0 compiler update, and may not affect versions prior to the 2026.0.0 release.
  • Fixed a bug that could cause simulations using multiple GPU devices to issue repeated ‘CUDA Driver API error’ throughout the simulation when running on Linux.
  • Fixed a bug where parallel runs could stall when multiple runs try to access the same SGS xf file at the same time. If another TUFLOW instance is using an SGS xf file, TUFLOW will now wait for it to release the file before continuing.

1D Network Domains – EPA SWMM

  • Fixed a bug that on rare occasions could cause an unhandled Fortran exception when running models with EPA SWMM input.
  • Fixed an issue with HEC-DSS file support for boundary conditions. This issue caused ERROR 0648 to be generated when reading boundary data from any .dss file. HEC-DSS files are supported on both Windows and Linux builds.
  • Fixed a bug that could cause WARNING 0627 to be issued when reading boundary .csv files, this caused XF Files to be disabled for the relevant CSV. This only occurred for wide files with more than 1,000 characters on a single line.
  • Fixed a bug that could generate duplicate rainfall timesteps with null rainfall depths when a material initial loss was applied in conjunction with 2d_sa_rf or global rainfall boundaries.
  • Fixed several bugs affecting SA polygons when the input polygon(s) contained multipart geometry. Multipart SA polygons could cause memory allocation errors in Classic and HPC models, and duplicate SA boundaries in Quadtree models. Multipart SA polygons now correctly apply a single boundary inflow in Classic, HPC, and Quadtree.

Outputs and Check Files

  • Fixed a bug that could cause ERROR 0636 when writing the domain check file while using GIS Format == GPKG.
  • Fixed a bug that caused the Finished line not to be written to the Global Simulation Log. This did not affect the simulation log in the model runs folder.
  • Fixed a bug that could cause incorrect Qmax values in the RLL_Qmax.csv result file. This issue occurred only in rare cases when the TUFLOW HPC 2D solver continued running for several timesteps after the 1D solver had completed.
  • The map output interval is no longer logged in the .tlf when also using Gauge Level Outputs (GLO) and CHECK 2663 is issued. GLO replaces the conventional approach of using a Start Map Output time and a Map Output Interval (i.e. it is not possible to get map outputs using a gauge location and also at regular intervals). Previously the map output interval was reported in the .tlf even though it was not used.
  • Made writing XMDF files across a network more resilient. Writing outputs to a network drive can sometimes run into instability issues if access is interrupted, even for a short time. Users reported times when XMDF files would fail to write and go into a retry loop before eventually failing. TUFLOW now attempts to reconnect to the XMDF file if a failure occurs. Testing has suggested that this has increased resilience when writing across the network.