You can easily fix this error by going into the site manager and adjusting your connection details to use plain FTP. Follow these steps to fix the problem:
In FileZilla, click on the File menu and choose Site Manager
Add the site or server you want to connect to if it’s not already in the site manager.
Add hostname
change the encryption to only use plain FTP
Change the logon type to Normal
Enter username/password.
Click on Connect to continue
If the problem persists, please disable your firewall then try once more! If it still fails, here is what you need to do:
Open Filezilla, go to Edit -> Settings
Click on Connection -> FTP: Choose Active
Click on Connection -> FTP -> Active Mode: Select Ask your operating system for the external IP address
Click on Connection -> FTP -> Passive Mode: Choose Fall Back to Active Mode
Press OK.
Try connecting to your FTP again!