Issue to access FTP

Question

Hi,

I tried to get to the new FTP and got the issue below, having the certificate SSL as well. What to adjust on the server?

Answer 1

For IIS FTP, IIS_IUSRS is usually not the account you need to grant access to. That group is for the IIS worker process (web app pool identity), not FTP authentication.

FTP uses the authenticated user's own credentials:

1. Basic authentication: the actual Windows account the client logs in as (local or domain user). That user needs NTFS permissions on the folder.
2. Anonymous authentication: the IUSR account (note: IUSR, not IIS_IUSRS).

So which account to add depends on how you set up FTP auth in IIS Manager then site then FTP Authentication:

1. If Basic is enabled and users log in as, say, ftpuser, add that user to the Temp folder's NTFS permissions.
2. If Anonymous is enabled, add IUSR.

Answer 2

Hi @Jonathan

You are using windows OS right. please check Event viewer while open this FTP application.

Goto Start->Search->type EventViewer->Windows Logs->Application and system check the both logs. if any error found share the screenshot. first understand the error then guide you how to fix this.

please share the application details. like application name and version.

Thanks.

Answer 3

vsftpd.conf does not exist on Windows: vsftpd is a Linux daemon. On Windows Server 2025 you use IIS FTP Server, configured through IIS Manager or %windir%\System32\inetsrv\config\applicationHost.config (the <system.ftpServer> section).

Windows File Explorer cannot do FTPS: It only speaks plain, unencrypted FTP. If your server requires SSL, Explorer will fail with that exact generic "Windows cannot access this folder" error. You can use FileZilla or WinSCP instead.

Answer 4

On the FTP server, verify and adjust these settings:

1. Configure FTP bindings and SSL

• In IIS Manager, select the FTP site.
• Open FTP SSL Settings.
• In SSL Certificate, select the installed SSL certificate that should be used for the FTP site.
• Under SSL Policy, choose:
  • Allow SSL connections if both plain FTP and FTPS should be allowed, or
  • Require SSL connections if all clients must use FTPS.

2. Verify FTP binding and port

• In the FTP site’s bindings, ensure the correct IP Address and Port are configured (typically 21 for FTP, 990 for implicit FTPS).
• If using implicit FTPS, configure port 990 as noted in the FTP security settings.

3. Ensure authentication and authorization are set correctly

• In the Add/Configure FTP Site wizard or FTP Security settings:
  • Choose the appropriate Authentication (Anonymous or Basic).
  • Under Authorization, ensure the correct users/groups are allowed and that Read and/or Write permissions are selected as required.
• Confirm that the Windows file system permissions on the FTP root and user folders match the FTP authorization settings.

4. If using user isolation or shared hosting

• When deploying FTP in a shared hosting scenario, configure user isolation so each user is restricted to their directory and cannot navigate above it. Ensure the user’s physical/virtual directory exists and is accessible.

After these adjustments, retry the connection from the client. If the error persists, re-check that the client is using the correct protocol (FTP vs FTPS), hostname, port, and credentials.

---

References:

• FTP over SSL <ssl>
• FTP Security <security> element
• FTP Site-level Settings <ftpServer>
• Guide to Deploy FTP and Publish with VWD
• Default FTP Security Settings <security>
• Configuring the FTP Adapter
• Known Issues with the FTP Adapter