Dear all, I am happy to report that NEST seems to work find under macOS 11 Big Sur. So far, I have only tested on Intel hardware, a system with the Apple M1 chip is on its way. Specifcially, I proceeded as follows: 1. After upgrading to Big Sur, run "brew doctor" and follow the instructions to update the Apple Command Line Tools. If you encounter problems, see https://stackoverflow.com/questions/64821648/homebrew-fails-on-macos-big-sur 2. Run "brew update" and "brew upgrade". 3. For safety's sake, I then ran "brew uninstall nest" and then "brew install nest". This gave me a working NEST 2.20.0 installation. To build NEST myself, I first performed steps 1 and 2 above and then 3. conda update conda conda create -n nest_dev nomkl numpy scipy matplotlib ipython cython nose conda activate nest_dev pip install junitparser The nomkl package ensures that NumPy does not use Intel's MKL, which can lead to conflicting OpenMP libraries. Junitparser is needed to handle testsuite results and is only available from PyPI. 4. Pull latest sources from NEST master branch to src 5. mkdir bld cd bld cmake -DCMAKE_INSTALL_PREFIX:PATH=<install path> -Dwith-mpi=ON ../src make -j4 install && make installcheck All tests pass. If many MPI tests fail, you may need to add --oversubscribe to the mpirun command in your .nestrc file. C++ tests will only run if you have installed boost, e.g., with "brew install boost". Best regards, Hans Ekkehard -- Prof. Dr. Hans Ekkehard Plesser Head, Department of Data Science Faculty of Science and Technology Norwegian University of Life Sciences PO Box 5003, 1432 Aas, Norway Phone +47 6723 1560 Email hans.ekkehard.plesser(a)nmbu.no Home http://arken.nmbu.no/~plesser