SolverStudio_00_09_01_00 20150813d has been released. This contains an IronPython patch to work around an IronPython 2.7.4 and 2.7.5 bug. This bug causes the error “SystemError: Handle is not initialized” in “_weakrefset.py”, line 73, within __contains__().
For more information, see https://mail.python.org/pipermail/ironpython-users/2015-April/017448.html and https://github.com/IronLanguages/main/issues/1187
Many thanks to SolverStudio user Andres Sommerhoff for following this up and suggesting this patch.
If you have not encountered this error, then there is no advantage in upgrading.
Note: The download file is named “SolverStudio_00_09_01_00 20150813d.zip”, with the “d” indicating the change to the IronPython “_weakrefset.py” file.