Hi, I am running to virtual hosts on Apache2 server. Those two virtual hosts run the same Python code the only difference is the domain name (and SSL certs). Two domains pointing to the same application. I am using flask with wsgi_mod 4.5.17 python 3.6.9 when I use lxml 4.2.5 there is no problem but when I use lxml 4.3.4 (or 4.5.1) I am getting following error in Apache log file when accessing the second host: [Sat May 30 15:54:38.456844 2020] [wsgi:error] [pid 26355:tid 140326337488640] [client xxx.xxx.xxx.xxx:50435] import lxml.etree as et, referer: https://first_host [Sat May 30 15:54:38.456882 2020] [wsgi:error] [pid 26355:tid 140326337488640] [client xxx.xxx.xxx.xxx:50435] ImportError: Interpreter change detected - this module can only be loaded into one interpreter per process., referer: https://first host I use following wsgi_mod config (I tried with processes=1 but no difference) WSGIDaemonProcess abc3 threads=10 display-name=abc3 -- jacek