Most FTP errors trace back to one of four causes: wrong credentials, a firewall blocking the passive-mode port range, wrong file permissions, or a mismatched transfer type. Check credentials first (host, username, password, port), then work through the specific error below.
530 login authentication failed
This means the server rejected your username or password before a connection was even established. Double-check you're using the full FTP username, not just the account login, and that the password hasn't been reset. If you're connecting to an account-level FTP user, confirm it still exists and wasn't recreated with a new password.
Also check the host: use your domain or server hostname exactly as issued, not an IP address unless that's what was provided. A typo in the host field often surfaces as a 530 rather than a connection error, because some clients silently fall back to a default port or protocol.
425 / can't open data connection (PASV issues)
A 425 error almost always means the client can log in but can't open the second connection FTP needs to actually transfer files (the "data channel"). This is nearly always a firewall or router problem on the client side, not the server. Try these in order:
- Switch your FTP client to passive mode (PASV) instead of active mode. Passive is the default in most modern clients and works through NAT and most firewalls; active mode requires the server to open a connection back to you, which routers usually block.
- If passive mode is already on and you still get 425, a local firewall, antivirus, or VPN is likely blocking the passive port range. Temporarily disable it to confirm, then add an exception instead of leaving it off.
- Try a different network. Some corporate and public Wi-Fi networks block outbound FTP entirely.
553 / 550 permission denied or file unavailable
These errors mean the FTP connection worked but the account doesn't have rights to read, write, or delete at that path. Common causes:
- Wrong directory scope. If the FTP account was created with a restricted home directory, it can only see files inside that folder, not the full site.
- File or folder permissions. Web files should generally be 644 and directories 755. If a file was uploaded with a restrictive mode (600 or lower) by a different process, subsequent FTP uploads or overwrites to it will fail. Fix permissions from File Manager or an SSH session before retrying.
- Read-only paths. Some system directories aren't writable by design. If you're trying to write outside your web root, that's expected behavior, not a bug.
Stalled, timed-out, or corrupted transfers
If a transfer hangs partway through or the uploaded file doesn't match the original:
- Set binary transfer mode for anything that isn't plain text: images, zip files, PDFs, executables. ASCII mode (the default in some older clients) rewrites line endings and will corrupt binary files byte by byte.
- Large files timing out usually means an idle timeout on your network or client, not the server. Increase the client's timeout setting or switch to SFTP if your client supports it.
- Partial uploads left behind after a failed transfer can cause "file already exists" conflicts on retry. Delete the partial file before uploading again unless your client explicitly supports resume.
Can't connect at all
If the client can't even reach the server (connection refused or timed out), confirm you're using the right port for the protocol you're connecting with. These are different protocols with different login mechanics, and a client configured for one won't connect on the other. Also confirm DNS for your domain is pointing at the right server. If you recently changed nameservers or DNS records, propagation delay can leave FTP unreachable even though the site loads fine over HTTP from a cached edge.
When to contact support
If you've confirmed credentials, switched to passive mode, checked file permissions, and you're still locked out, open a ticket from the portal (Support → New ticket), use live chat, or email.