After bug #688100 was closed (thanks!) I discover that dev-python/aiorpcX-0.18.3 has some changes in the API that break net-misc/electrum-3.3.6 again. See bug #687004 Reference: https://github.com/kyuupichan/aiorpcX/blob/master/docs/changelog.rst "Version 0.18.0 (09 May 2019) ... Unfortunately this required changing several APIs. ... The old Connector and Server classes are gone." So net-misc/electrum-3.3.6 needs exactly =aiorpcX-0.17.0 (I tested it...) which is the only released 0.17.x version. Please add dev-python/aiorpcX-0.17.0.