FileZilla Certificate Warning: Verify FTPS Certificates Safely
Quick answer
A certificate warning means the FTPS server certificate could not be accepted automatically. Verify the hostname, issuer and fingerprint before continuing.
What to check first
Confirm the exact protocol, hostname, port and error message before changing settings. Separate client-side network issues from server-side authentication, permission or configuration problems.
Windows troubleshooting
Check Windows Firewall, VPN or security software only when the symptom points to local filtering. Prefer reversible changes and retest after each step.
Server-side checks
If the connection reaches the server but a specific operation fails, review server logs, account permissions and protocol configuration rather than repeatedly reinstalling the client.
Frequently asked questions
What should I check first?
A certificate warning means the FTPS server certificate could not be accepted automatically. Verify the hostname, issuer and fingerprint before continuing.
Should I reinstall FileZilla immediately?
Usually no. Reinstallation rarely fixes server permissions, firewall rules, protocol mismatches or account limits. Diagnose the exact failure first.