Mac OS X: OpenVPN error: write UDPv4: Can't assign requested address (code=49)

When using OpenVPN in Mac OS X, you may encounter the problem:
Mac cannot connect to server, while other devices in the same LAN, even the Windows VM in this OS X works fine. It works again after reboot.
If you check the log, you may see this:

OpenVPN error: write UDPv4: Can’t assign requested address (code=49)

I used to reboot to solve this. But there is a better quicker way, provide by anuson.com

• Open a Terminal window. (Found in Applications -> Utilities.)
• Enter the following commands:
  1. sudo ifconfig en1 down
  2. sudo route flush
  3. sudo ifconfig en1 up
• Please make sure to replace en1 with your actual Internet interface.
• If you don’t know which en interface is your Internet interface you can do a:
  1. sudo ifconfig
• To get an overview and figure our which en interface is your Internet interface.

Check original post in anuson.com