| Description | This article describes the scenario where FortiClient has been uninstalled but the user is still getting 'A more recent version of FortiClient is already installed' or 'You must uninstall other versions of FortiClient' when trying to install a previous version. |
| Scope | FortiClient v7.x.x, v6.x.x. |
| Solution |
When trying to downgrade FortiClient, the following error can appear even when the version has already been uninstalled:
Verify if the entry is present within 'Add or Remove Programs' within Windows. If it is, uninstall it and try again. If the error still occurs, it is necessary to use the FortiClient removal tool. This will be inside support.fortinet.com, under Firmware Download -> FortiClient -> Download. Select the version, then download the highlighted file:
The tool will be under FortiClientTools_x.x.x> SupportUtils > FCRemove.exe.
Run the program, and follow the instructions. It will ask to reboot. Once this is done, try again.
If it still is giving this error, it is most likely due to a latent registry key. It is then necessary to remove this manually. It is highly recommended to do a system restore point whenever touching the registry, as there is a risk of damaging the OS if changes are made to the wrong registry keys.
Open up regedit.msc, then navigate to HKEY_CLASSES_ROOT\Installer\Products. A list of UUIDs should be visible like seen in this picture:
Find the one with the 'ProductName' value as 'FortiClient VPN'. This is the registry key necessary to delete. Make sure to have the right one! Simply 'right-click', then hit delete.
Search on the Registry via the UUID. You can verify the UUID by opening the installation log.
Folder Directory: 'C:\Users\<username>\AppData\Local\Temp' File Name: FortiClientxxxxx
After this, it will be possible to install FortiClient normally. If there are any difficulties even after deleting the registry key, open up a ticket with TAC. |
