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Gulbeyaz
Gulbeyaz
Explorer II
March 15, 2025
Question

Forticlient SSL VPN Connection down: Permission denied

  • March 15, 2025
  • 11 replies
  • 27645 views

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

11 replies

MZBZ
Staff
MZBZ
Staff
March 16, 2025

Uninstall and then wipe-clean using fcremove.exe:

https://community.fortinet.com/t5/FortiGate/Technical-Tip-How-to-download-FortiClient-and-FCRemove-exe-from/ta-p/218955

 

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

 

    Gulbeyaz
    GulbeyazAuthor
    Explorer II
    March 16, 2025

    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
    Staff
    Sheikh
    Staff
    March 16, 2025

    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/ta-p/190433

     

    regards

     

    Sheikh

    If you have found a solution, please like and mark it as solved to make it easily accessible for everyone.
      Gulbeyaz
      GulbeyazAuthor
      Explorer II
      March 16, 2025

      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
      Christian_89
      Contributor III
      March 16, 2025

      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
        GulbeyazAuthor
        Explorer II
        March 16, 2025

        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
        Christian_89
        Contributor III
        March 16, 2025

        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
          GulbeyazAuthor
          Explorer II
          March 16, 2025

          Please feel free to give advices

          Sheikh
          Staff
          Sheikh
          Staff
          March 17, 2025

          Hello @Gul ,

           

          What are the debug logs from FortiGate show ?

           

          diagnose debug reset
          diagnose debug application fnbamd -1
          diag vpn ssl debug-filter src-addr4 x.x.x.x (Replace x.x.x.x with the IP address of the PC connected to the SSL VPN, the one give by the connection)
          diagnose debug app sslvpn -1
          diagnose debug enable

           

          regards,

           

          Sheikh

          If you have found a solution, please like and mark it as solved to make it easily accessible for everyone.
            Gulbeyaz
            GulbeyazAuthor
            Explorer II
            March 19, 2025

            Hello! So I did not come across the solution of this exact problem but I figured something else.I couldn't manage to download the version that I use before and worked for me but I found an another version of forticlient and used it and it worked for me. I come across to another article which include one of my problems and felt like it would work too. So I am not gonna mark anything as a solution because we didn't come across with my problem but if you are someone looking for a solution with a close problem this is what I did!

             

            https://community.fortinet.com/t5/Support-Forum/I-Need-install-Forticlient-VPN-7-0-8-0427/td-p/312806/page/2

             

            https://community.fortinet.com/t5/FortiGate/Troubleshooting-Tip-SSL-VPN-fails-at-98/ta-p/248363

            Gulbeyaz
            GulbeyazAuthor
            Explorer II
            November 5, 2025

            Hi back then I deep cleansed my laptop multiple times and it didn't work for me still so I ended up with the old apk version but after a year it stopped working then I shoot my shot with the original, recent one again then it worked. I think they changed something. My uni or the contributors. I really don't know tho. Thanks for your reply

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