I did some digging: The issue here is that sys.path is not being correctly configured
It is being initialized to: ['', '/tmp/cpython/lib/python310.zip', '/tmp/cpython/lib/python3.10', '/tmp/cpython/lib/python3.10/lib-dynload'] not: ['', '/tmp/cpython/lib/python310.zip', '/tmp/cpython/lib/python3.10', '/tmp/cpython/lib/python3.10/lib-dynload', '/tmp/cpython/lib/python3.10/site-packages'] You can verify this by running: esysparticle -c 'import sys; print(sys.path)' More digging showed that it is actually being correctly initialized in Py_Initialize(), but then re-initialized to be incorrect in Py_Main(). A git bisect got me to https://github.com/python/cpython/commit/af1d64d9f7a7cf673279725fdbaf4adcca51d41f as being the commit that made that change. I haven't got to the bottom of exactly why that reinitialization is going wrong, but these bugs hint at this code as being unsupported: https://bugs.python.org/issue36204 https://bugs.python.org/issue34008 The easy answer here is to stop calling Py_Initialize(), as it's not necessary. The "right" long-term approach would be to migrate to Py_RunMain(). SR -- Stefano Rivera http://tumbleweed.org.za/ +1 415 683 3272