Mac OS X: 10.15.5 Download httpd-2.4.46.tar.bz2 apr-1.7.0.tar.gz apr-util-1.6.1.tar.gz Steps cd httpd-2.4.46 mv apr-util-1.6.1 httpd-2.4.38/srclib/apr-util mv apr-1.6.5 httpd-2.4.38/srclib/apr ./configure --with-included-apr --with-apr-util make ... In file included from ./include/apr_encode.h:24: ./include/apr.h:561:2: error: Can not determine the proper size for pid_t #error Can not determine the proper size for pid_t ^ In file included from encoding/apr_encode.c:30: In file included from ./include/apr_strings.h:52: ./include/apr_want.h:94:8: error: redefinition of 'iovec' struct iovec ^ /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_iovec_t.h:31:8: note: previous definition is here struct iovec { ^ 2 errors generated.