Ahven 2.6 is almost identical to 2.5, but its documentation contains fixed release dates.
Hosting and other changes
There aren't many code changes. Instead, the build mechanism for GNAT is changed and the hosting of Ahven is also moved to a dedicated site. New releases do not appear at SourceForge, since it has been injecting adware to many projects (not yet Ahven, though).
New download location is http://www.ahven-framework.com/releases/
The building on Linux using GNAT now happens with comfignat.mk Makefile template. Normal users should not see much changes, but distribution packagers should have better configuration options. The change was a wish from Fedora packagers. One of them, Bjorn Persson, contributed the comfignat scripts for Ahven.
Another change related change is that the documentation needs to be build using Sphinx. Previously, Ahven's release tarballs have included the prebuilt documentation, but this caused some problems for Debian developers because their packaging policy warns about prebuilt things.