On one of my servers, I had the exact same problem. No matter what options I choose to export, I got a blank white screen when I clicked EXPORT PACKAGE. Both servers are on php 5.4. I compared the php.ini files and we had disabled a number of functions on the production server for security. When I reenabled those functions, it started working. I’m not sure which function is required, but here is the list of functions that we had disabled. Commenting out the disable allowed All-in-One WP Migration to work again. Any idea which function(s) in particular is required?
;disable_functions = php_uname, getmyuid, getmypid, passthru, leak, listen, diskfreespace, tmpfile, link, ignore_user_abord, shell_exec, dl, exec, system, highlight_file, source, show_source, fpaththru, virtual, posix_ctermid, posix_getcwd, posix_getegid, posix_geteuid, posix_getgid, posix_getgrgid, posix_getgrnam, posix_getgroups, posix_getlogin, posix_getpgid, posix_getpgrp, posix_getpid, posix, _getppid, posix_getpwnam, posix_getpwuid, posix_getrlimit, posix_getsid, posix_getuid, posix_isatty, posix_kill, posix_mkfifo, posix_setegid, posix_seteuid, posix_setgid, posix_setpgid, posix_setsid, posix_setuid, posix_times, posix_ttyname, posix_uname, proc_open, proc_close, proc_get_status, proc_nice, proc_terminate
