Forticlient SSL VPN Connection down: Permission denied

[Gulbeyaz]

Hi! So I have a problem with my VPN connection. I had Forticlient VPN 2 years before with the same settings that I try to run it right now. It was running exactly fine but I deleted it because I wasn't using it anymore. 2 years later and right now I am trying to run it again but I am getting "SSL VPN Connection down: Permission denied" error. It is a problem with my pc because I can log in to my friends computer with my student number. My university advicing me to reset my pc but I don't exactly want to. Is there any solution to my problem? Can you please help me with that?

FortiClient

[MZBZ]

Uninstall and then wipe-clean using fcremove.exe:

https://community.fortinet.com/t5/FortiGate/Technical-Tip-How-to-download-FortiClient-and-FCRemove-e...

Then reinstall the latest version of the client software and try again.

[Gulbeyaz]

Hello! I don't have forticlient EMS. I am using the free version. With the guide you sent I searched FCRemover.exe in community and found some .zip document. Used it and it said I should reboot everything is done. But my problem is still existing. In notification segment it says the error code is -455 I am not sure if it would help but yeah nothing changed but thank you if you have more suggestion please reply me 

[Sheikh]

hello @Gulbeyaz 

The debug logs from FortiClient might also give some clues.

https://community.fortinet.com/t5/FortiClient/Technical-Tip-How-to-enable-debug-log-in-FortiClient/t...

regards

Sheikh

[Gulbeyaz]

Hey! So please excuse me for that but I really have not got so much information about this subject. What should I do with log that I create and even if I select debug I am really not sure I am correctly running it so do you have more detailed article about it? or may you enlighten me more? If so I would appreciated it a lot. Thank you.

[Christian_89]

Here are the troubleshooting steps for the FortiClient SSL VPN "Permission denied" error

Verify Credentials and Authentication 
- Ensure that the username and password are entered correctly
- If your university uses multi-factor authentication, make sure all required steps are completed

Check FortiClient Version 
- Older versions of FortiClient may no longer be compatible with the university’s VPN settings
- Uninstall FortiClient completely
- Restart the computer
- Download and install the latest version of FortiClient from the official Fortinet website

Run FortiClient as Administrator
- Right-click on the FortiClient icon and select "Run as administrator"

Remove Old FortiClient Configurations 
- Open File Explorer and delete old FortiClient configuration files
- Go to the following folders and delete their contents
- C Program Files Fortinet
- C Program Files x86 Fortinet
- C Users YourUsername AppData Local Fortinet
- C Users YourUsername AppData Roaming Fortinet
- Restart the computer and reinstall FortiClient

Check Windows Firewall and Antivirus
- Open "Windows Defender Firewall" in the Control Panel
- Ensure that FortiClient is allowed for both private and public networks
- If a third-party antivirus is installed, temporarily disable it and test the connection

Adjust SSL and TLS Settings in Internet Explorer
- Open Internet Explorer and go to "Settings" then "Internet Options"
- Go to the "Advanced" tab and scroll down to the security settings
- Ensure that TLS 1.1 and TLS 1.2 are enabled
- Ensure that SSL 2.0 and SSL 3.0 are disabled
- Click "Apply" and restart the computer

Check VPN Log Files
- Open FortiClient and go to "Settings"
- Select "View Logs"
- Look for error messages such as
- Server certificate verification failed
- No response from remote gateway
- Permission denied

Import SSL VPN Certificate
- If the university uses a self-signed certificate, FortiClient may require the correct certificate
- Ask the university for the correct SSL VPN certificate
- Open the certificate manager by pressing Windows key and R and typing "mmc"
- Go to "File" then "Add Remove Snap-in"
- Select "Certificates" then "Computer Account" and then "Local Computer"
- Import the certificate under "Trusted Root Certification Authorities"
- Restart the computer and test the connection

Reset Network Settings
- If all previous steps fail, there may be an issue with the network settings
- Open Command Prompt as Administrator and run the following commands
- netsh int ip reset
- netsh winsock reset
- ipconfig flushdns
- ipconfig release
- ipconfig renew
- Restart the computer and try connecting again

If the issue persists, you can run FortiClient in debug mode
- Open Command Prompt as Administrator
- Run the following command
- C Program Files Fortinet FortiClient FortiClient exe debug
- Try connecting and check the log files for detailed error messages

Try these steps and let me know which solution worked for you

[Gulbeyaz]

Hello. I tried everything you listed but the last one because command prompt didn't take the command as a command. Nothing worked. Thank you tho! If you have more advices please feel free to share with me I really don't want to reset my computer

[Christian_89]

Here are a few additional suggestions you can try if all earlier steps did not resolve the issue and you want to avoid resetting your computer

Check Date and Time Settings
- Ensure that your system date and time are correct
- Mismatched time can cause certificate validation failures

Try a Different Network
- Attempt connecting from a different Wi Fi or mobile hotspot
- If it works on another network, there may be local firewall or network restrictions on your primary connection

Disable IPv6 Temporarily
- Open Network and Internet Settings
- Go to Change Adapter Options
- Right click on your active network adapter and select Properties
- Uncheck Internet Protocol Version 6 IPv6
- Click OK and test the VPN again

Run System File Checker and DISM
- Open Command Prompt as Administrator
- Run sfc scannow
- Wait for the scan to complete
- Then run DISM online cleanup image restorehealth
- Restart your computer after each step
- These commands fix possible Windows system file corruptions

Check for Third Party Software Conflicts
- Uninstall or disable any other VPN software or network filter
- Temporarily disable third party firewalls or security tools beyond antivirus
- Some endpoint protection programs conflict with FortiClient

Try a Different Version of FortiClient
- If the latest version fails, install an older supported version
- Sometimes new versions introduce changes that do not work well on certain systems
- Restart the computer after installing the older version

Use the Web based SSL VPN Portal if Available
- If your university offers a web browser based SSL VPN portal, log in there to confirm that your account and credentials are valid
- If the web portal works, the issue is likely tied to the local FortiClient installation

Reinstall or Update Network Adapter Drivers
- Open Device Manager
- Expand Network Adapters
- Right click on your primary Ethernet or Wi Fi adapter
- Select Update Driver or Uninstall Device and reboot to allow Windows to reinstall
- After that, retest FortiClient

Check Event Viewer
- Press Windows key plus R, type eventvwr and press Enter
- Go to Windows Logs then Application and System
- Look for errors or warnings related to FortiClient or network connectivity around the time you attempt the VPN connection

Try Creating a New Windows User Profile
- Sometimes user profiles get corrupted and affect VPN software
- Create a new local user with administrator rights
- Log in with that new user and install FortiClient
- Attempt to connect from the new profile

Ask the University for Updated Credentials or Certificate
- Confirm that your account is not locked or expired
- Verify that the certificate or any unique token used for VPN authentication is still valid

If none of these steps help, you could share some of the Windows Event Viewer logs with the university helpdesk or FortiNet support for more in depth troubleshooting. This can sometimes pinpoint an underlying system issue without requiring a full system reset. Let me know if you have any questions about the steps above

[Gulbeyaz]

Please feel free to give advices