1. FTP client sends a DNS query for the domain name to get the FTP server IP address (if you are using ftp.domain.com as FTP hostname).
   
   
2. DNS responds back with the IP address.
   
   
3. FTP client and server complete three-way handshake process.
   
   
4. The FTP server then sends a 220 response to indicate that the FTP server is ready to accept a login.
   
   
5. The FTP client sends Username through USER command, and Password through PASS command.
   
   
6. FTP Server verifies the provided login information.
   
   
7. If provided login details are correct, the FTP server will in turn sends a Welcome message.
   
   
8. FTP client requests a directory listing.
   
   
9. FTP server transfers the requested listing.
   
   

After specifying FTP credentials, If FTP user does not have the required privileges, you may receive the following error message in the FTP client:

Status: Resolving address of ftp.xxxxx.com
Status: Connecting to xxx.xxx.xxx.xx:21...
Status: Connection established, waiting for welcome message...>
Response: 220 Microsoft FTP Service
Command: USER Administrator
Response: 331 Password required for Administrator.
Command: PASS ***************
Response: 530 User cannot log in, home directory inaccessible.
Error: Critical error
Error: Could not connect to server

In most cases, this error occurs only when FTP authorization rules for the default FTP site are not set.

How to fix this error by changing FTP authorization rules!

1. Login to the VPS via Remote Desktop connection as an Administrator user. Please refer to how to connect windows VPS using RDP for more details.
   
   
2. Open IIS [Start → Administrative Tools → Internet Information Service].
   
   
3. Expand Sites option from left pane.
   
   
   
   
4. You will see a Default FTP Site in site list, expand this website.
   
   
   
   
5. Now, double click on FTP Authorization Rules option from the center pane.
   
   
   
   
6. From the right pane, click on Add Allow Rule.
   Get Windows VPS
   
   
   
7. Select the option of All Users and tick the check box of Read and Write permission.
   
   
8. Click on OK button to save the changes and Restart Microsoft FTP Services to reflect them.
   
   
   
   

Follow below-mentioned steps to restart Microsoft FTP Services:

1. Open Services [Start → Run → type services.msc and Hit Enter].
   
   
2. Select the service named Microsoft FTP Service.
   
   
3. Click on Restart link from the left pane option.
   
   

Now, try again to login to the FTP account. If everything goes fine, then you should not receive any error while connecting to your FTP account.

To avoid such errors, FTP accounts should be created with appropriate permissions. I have linked the article to properly set up the FTP account from IIS.

→ Looking for any other help with FTP? Don't forget to check out our Complete FTP Guide.

→ Are you facing an FTP error at Filezilla? Please refer to Fix FTP error for more details. 

→ Are you facing an FTP with too many connections error? Please refer to Fix FTP too many clients error for more details.