Hi Zacchaeus! Thanks for the report! I think, synapse 1.30.1 changed the dependency of python-cryptography to a newer version (which we currently have as python-cryptography-next). But also python-pyopenssl and python-pysaml2 needs to be build with cryptography-next [1] (or they fail in a byte2int() or similar at runtime somewhere). So we also need some more -next python packages to upgrade synapse from 1.29. matrix-common is needed from version >=1.50. Footnotes: [1] http://www.rohleder.de/gitweb/?p=guix.git;a=blob;f=mroh/guix/packages/python.scm;h=13ce4e8dd9822f443633385af6203fef78e198aa;hb=HEAD#l79 -- There are two ways of constructing a software design. One is to make it so simple that there are obviously no deficiencies; the other is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult.